• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.456-470
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• 2013

Hollow-fiber membranes, is one of the new technologies that is growing rapidly in the past few decades. In addition, separation membranes using polymer materials, have attracted attentions in various fields including gas separation, fuel cells, water treatment, wastewater treatment, and organic separation. Nanofiltration (NF) membranes having the separation characteristics in the intermediate range between ultrafiltration and reverse osmosis (RO) membranes for liquid separation, with relatively low investment cost and operating pressure lower than that of RO membranes, have high permeance and rejection performance of multivalent ions as well as organic compounds of molecular weight between $200{\sim}1000gmol^{-1}$. In this paper, we would like to review the research trends on the various structure control and characterization of NF hollow fiber membranes with respect to materials and the methods of preparation (phase inversion method and interfacial polymerization method). Currently, most of NF membranes have been manufactured by plate and frame types or spiral wound types. But hollow fiber types have delayed in commercial products, because of the weak strength when to produce on the basis of the existing materials, therefore the development of new materials or improvement of existing materials will be needed. If improving manufacturing technology is available, hollow fiber types will replace spiral wound types and gradually show a higher market share.

• Applied Biological Chemistry
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• v.44 no.4
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• pp.219-223
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• 2001

Effects of hemoglobin (Hgb) concentration and degree of hydrolysis (DH) of Hgb on the separation of heme-iron were examined to produce highly enriched heme-iron from Hgb hydrolysate. Separation efficiency of Hgb hydrolysate with different DH was studied at wide pH range (pH $1.0{\sim}11.0$). Separation efficiency expressed as heme-iron/peptide ratio increased with decreasing Hgb concentration. When 5% Hgb (pH 10.0) was hydrolyzed using commercially available Esperase for 5 h at $50^{\circ}C$, DH was 25%. The precipitation of heme-iron-enriched peptides were remarkably high at pH range $3{\sim}6$. Optimal pH range for heme-iron with high heme-iron/peptide ratio shifted to acidic pH with increasing DHs of Hgb. The enriched heme-iron fraction in the precipitates showed a single band through urea-SDS-PAGE, with a molecular mass of 1 kDa. In the dry heme-iron product produced in a pilot bioreactor, content of heme-iron and heme-iron/peptide ratio were 27.1 and 38.7%, respectively, and production yield was 9.3%.

• Korean Journal of Food Science and Technology
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• v.21 no.4
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• pp.542-548
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• 1989

For the selective separation of proteins, the solubilization and desolubilization of proteins in sodium-di-2-ethylhexyl sulfosuccinate (AOT)-isooctane reverse micellar system were investigated. Protein solubilization increased with increasing the concentration of AOT to 200 mM and then decreased above that concentration. Protein was solubilized into reverse micelles in the pH range below the isoelectric Point of each protein, pH 4-10 for lysozyme and pH 5-6 for trypsin and ${\alpha}-chymotrypsin$, Lysozyme, trypsin and ${\alpha}-chymotrypsin$ were efficiently extracted in the precence of KCl and NaCl while larger molecular weight proteins such as pepsin and BSA had high solubilization with $CaCl_2$. At higher ionic strength all proteins exhibited murk less tendency to solubilize and the increase of ionic strength resulted in the decrease of micelle size. Lysozyme was successfully back transfered at pH 12.2 and 1.0M KCl; trypsin at pH 12.6 and 0.5M KCl; and ${\alpha}-chymotrypsin$ at pH 6.7 and 0.5M KCl. In a test group separation experiments, complete separation of lysozyme from BSA could be obtained.

• Membrane Journal
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• v.20 no.4
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• pp.312-319
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• 2010

Carbon membrane materials have received considerable attention for the gas separation including hydrocarbon mixture of ingredients of the volatile organic compounds(VOCs) because they possess their higher selectivity, permeability, and thermal stability than the polymeric membranes. The use of activated carbon membranes makes it possible to separate continuously the VOCs mixture by the selective adsorption-diffusion mechanism which the condensable components are preferentially adsorbed in to the micropores of the membrane. The activated carbon hollow fiber membranes with uniform adsorptive micropores on the wall of open pores and the surface of the membranes have been fabricated by the carbonization of a thin film of phenolic resin deposited on porous alumina hollow fiber membrane. Oxidation, carbonization, and activation processing variables were controlled under different conditions in order to improve the separation characteristics of the activated carbon membrane. Properties of activated carbon hollow fiber membranes and the characterization of a gas permeation by pyrolysis conditions were studied. As the result, the activated carbon hollow fiber membranes with good separation capabilities by the molecular size mechanism as well as selective adsorption on the pores surface followed by surface diffusion effective in the recovery hydrocarbons have been obtained. Therefore, these activated carbon membranes prepared in this study are shown as promising candidate membrane for separation of VOCs.

• Clean Technology
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• v.29 no.2
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• pp.109-117
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• 2023

The purpose of this study is to develop a method for separating antioxidants and sugars from grape skin extract. The extract was first mixed with a variety of organic solvents to investigate whether the separation was feasible. When employing acetone, ethanol, dimethylsulfoxide, or dimethylformamide, the organic solvent-extract combination formed a single phase. However, when benzene, ethyl acetate, or n-hexane was added to the extract, the mixture separated into an organic and an aqueous phase and the pigments remained in the aqueous phase. On the other hand, when polyethylene glycol-2,000 (PEG-2000) and sodium citrate were added to the extract, the mixture was separated into three layers, with the majority of the flavonoids migrating to the top layer and 53% of the extract's glucose migrating to the bottom layer. The top layer had significant antioxidant activity, whereas the bottom layer showed no antioxidant activity. The glucose recovery in the bottom layer increased as the molecular weight of PEG increased and the highest recovery (67%) was observed when PEG-8,000 was added. The highest flavonoid separation was observed with PEG-2,000, followed by PEG-8,000 and PEG-400. The flavonoid separation when PEG-2,000 was added resulted in a flavonoid recovery of 48% and 0.2% from the top and bottom layers, respectively. Examining the effect of the separated solution using the agar disc diffusion method on yeast cell growth confirmed that the addition of the extract, the top, and the bottom layer did not inhibit cell growth.

• Membrane Journal
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• v.23 no.5
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• pp.332-342
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• 2013

In the present study, carbon molecular sieve (CMS) hollow fiber membranes were prepared by carbonizing a methyl imide hollow fiber precursor, which was spun by non-solvent induced phase separation process. And effects of carbonization parameters such as pre-oxidation, pyrolysis, and post-oxidation on the gas permeation were systematically investigated. CMS membrane having the highest gas flux was obtained by carbonizing the precursor through a combined process of air pre-oxidation at $250^{\circ}C$ for 2h, nitrogen pyrolysis at $550^{\circ}C$ for 2h, and oxygen post-oxidation at $250^{\circ}C$ for 2h. The optimized membrane showed a considerable gas permeance : the $H_2$, He, $CO_2$ permeances were 69.72, 35.61, 31.01 GPU, respectively, and the $O_2$ and $N_2$ permeances were ignorable. Therefore, it was clear that the prepared CMS hollow fiber membrane was a promising membrane for recovering small gases such as hydrogen and hellium and carbon dioxide.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.527-534
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• 2012

The adsorption dynamics of activated carbon (AC) and carbon molecular sieve (CMS) beds were studied to recover ethylene from FCC fuel gas. In this study, the FCC fuel gas used consisted of six-component mixture ($CH_4/C_2H_4/C_2H_6/C_3H_6/N_2/H_2$,32:15:14:2:12:25 vol.%). And the breakthrough experiments of adsorption and desorption were carried out. The breakthrough sequence in the AC bed was $H_2$ < $N_2$ < $CH_4$ < $C_2H_4$ < $C_2H_6$ while the sequence in the CMS bed was $H_2$ < $CH_4$ < $N_2$ < $C_2H_6$ < $C_2H_4$. The separation performance of the CMS bed during the adsorption step was lower than that of the AC bed. However, due to the characteristics of kinetic separation, the CMS bed could remove $CH_4/N_2$ as well asthe molecules that are larger than $C_2H_6$, which was not easy to be done by the AC bed. Since it was hard to regenerate the adsorption bed by simple depressurization, vacuum regeneration should be adopted. As a result, the pressure vacuum swing adsorption (PVSA) process, consisting of CMS pretreatment process and AC main process, was suggested to recover ethylene efficiently.

• Journal of Applied Biological Chemistry
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• v.44 no.4
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• pp.190-193
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• 2001

Genipin, aglycone of geniposide isolated from fruits of Gardenia jasminoides, was transformed into blue pigments through reaction with glycine and methylamine. The blue pigments formed from glycine-reacted genipin were passed through Bio-Gel P-2 resin yielding fractions GG1 and GG2, and those from methylamine-reacted genipin were separated into fractions GM1-GM4. The first eluted higher molecular-weight fractions, GG1 and GM1, had higher tinctorial strength than the later eluted lower molecular-weight fractions, GG2 and GM2-GM4, respectively. $^1H-NMR$ spectra of GG1 and GM1 showed very broad peaks indicating that structures of the pigments were highly polymeric. $^1H-NMR$ spectra of GG2, GM3, and GM4 showed several sharp peaks at aliphatic and aromatic regions with accompanying broad peaks, although the spectrum of GM2 was rather simple. Determination of the structural and physical nature of the isolated pigments is in progress.

• Environmental Mutagens and Carcinogens
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• v.26 no.1
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• pp.20-24
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• 2006

An antimicrobial substance was purified from the giant snail body extract (Achatina fulica) using solid-phase extraction and separation on HPLC reversed-phase chromatography. The primary structure were determined by a combination of an automated amino acid sequence and MALDI-TOF Mass. Its molecular mass was found to be 1392.64 Da. This result was in excellent agrement with the theoretical molecular mass calculated from the amino acid sequence. purified peptide showed antimicrobial activity in vitro against Escherichia coli D31. This result indicate that giant snail whole body was potentially antimicrobial.

• BMB Reports
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• v.32 no.4
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• pp.393-398
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• 1999

Acetolactate synthase (ALS) catalyzes the first reaction common to the biosynthesis of L-valine, L-leucine, and L-isoleucine. ALS is the target site of several classes of herbicides, including the sulfonylureas, the imidazolinones, and the triazolopyrimidines. Two forms of ALS (ALS I and ALS II) which have different affinity for Heparin have been separated from etiolated pea seedlings. The substrate saturation curves of both ALS I and ALS II were hyperbolic in contrast to previous reports. The two forms of ALS showed significant differences in their physical and kinetic properties. The values of $K_m$ for ALS I and ALS II were 9.0 mM and 4.8 mM, respectively. The pI values for ALS I and ALS II were determined to be 5.3 and 5.75 by isoelectric focusing, respectively. The native molecular weights for ALS I and ALS II obtained by nondenaturing gel electrophoresis and activity staining were 124 and 244 kDa, respectively. They also exhibited different sensitivity to feedback inhibition by end-product amino acids and inhibition by Cadre, an imidazolinone herbicide.