• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.38 no.2
• /
• pp.83-88
• /
• 2005

Protease inhibitors were purified from the eggs of Alaska pollock (Theragra chalcogramma) using the following purification steps: ammonium sulfate precipitation, ion exchange, gel permeation, and high performance liquid chromatographies (HPLC). The protease inhibitor from the heated eggs of Alaska pollock was not as well purified. In addition, the heated eggs showed lower specific inhibitory activity than the unheated eggs. The purification yields after ammonium sulfate precipitation, ion exchange, and gel permeation chromatographies were 22.7$\%,\;15.3\%$,and $4.4\%$, respectively. There were two kinds of protease inhibitors on the gel permeation chromatography pattern Their molecular weights were estimated to be 66,700 and 16,000 Da, respectively. Both were classified as a cysteine protease inhibitor because of the existence of inhibiting papain, which is one of cysteine proteases.

• Membrane Journal
• /
• v.14 no.2
• /
• pp.157-165
• /
• 2004

PU/PDMS(Poly urethane/poly(dimethylsiloxane ) membranes were prepared to enhance chemical resistance over VOCs from 4,4'-diphenylmethane diisocyanate (MDI), poly(dimethylsiloxane) (PDHS). Swelling characteristics and vapor permeation performance of toluene, 1,2-dichloroethane, hexane through PU/PDMS membrane with various feed VOCs concentration were investigated. Swelling ratio of VOCs showed tendency of Toluene > 1,2-dichloroethane > hexane. Fiux of toluene and 1,2-dichloroethane increased with increasing fled concentration while the flux of hexane maintained with increasing feed. VOCs concentration in permeate maintained 50 wt% oi concentration due to high affinity of PU/PDHS membranes to VOCs.

• Macromolecular Research
• /
• v.11 no.3
• /
• pp.163-171
• /
• 2003

For the pervaporation of water-ethanol mixtures, new composite membranes having poly(acrylic acid)-poly (butyl methacrylate-co-methyl methacrylate) interpenetrati ng polymer network [PAA-P(BMA-co-MMA) IPN] skin layer supported on porous and crosslinked poly(BMA-co-MMA) were prepared. The morphology of the sub-layer of the composite membrane prepared in the presence of 60 wt% solvent showed cellular structure, on the other hand that of sublayer prepared in the presence of 70 wt% solvent presented very porous interconnected pore structure with macrovoids. Permeation rates of the composite membranes were largely influenced by the morphology of the sublayer. Separation factors increased with the increase of the degree of crosslinking of the PAA network. It was found that permeation rates could be increased by introducing anionic charges on carboxyl groups of the PAA. The permeation rate changes of the PAA-P(BMA-co-MMA) IPN composite membranes according to the feed compositions showed quite similar pattern with the swelling behavior in water-ethanol mixtures.

• Membrane Journal
• /
• v.4 no.4
• /
• pp.205-212
• /
• 1994

Gas permeation properties of simple gases(He, $H_2,\;CO_2,\;O_2,\;N_2,\;CH_4$) through plasma-polymerized films were investigated, and the chemical structure of the plasma polymers was analyzed by infrared spectra. The plasma-polymerized films were prepared by plasma polymerization of fluorine-containing aromatic compounds, and permeation measurements were made at $35^{\circ}C$, latm. The permeability coefficient of the plasma films decreased as the size of penetrant molecules increased. The plasma polymers showed higher $CO_2/CH_4$ selectivities than those of commonly used polymers, while $O_2/N_2$ selectivities were similar of slightly lower than those of common polymers. FT-IR spectra shows that the plasma polymers contain both aromatic and aliphatic structures.

• Macromolecular Research
• /
• v.16 no.6
• /
• pp.555-560
• /
• 2008

A series of hydroxyl-group containing polyimides (HPIs) were prepared in order to investigate the structure-gas permeation property relationship. Each polymer membrane had structural characteristics that varied according to the dianhydride monomers. The imidization processes were monitored using spectroscopic and thermog-ravimetric analyses. The single gas permeability of He, $H_2$, $CO_2$, $O_2$, $N_2$ and $CH_4$ were measured and compared in order to determine the effect of the polymer structure and functional -OH groups on the gas transport properties. Surprisingly, the ideal selectivity of $CO_2/CH_4$ and $H_2/CH_4$ increased with increasing level of -OH incorporation, which affected the diffusion of $H_2$ or the solubility of $CO_2$ in HPIs. For $H_2/CH_4$ separation, the difference in the diffusion coefficients of $H_2$ and $CH_4$ was the main factor for improving the performance without showing any changes in the solubility coefficients. However, the solubility coefficient of $CO_2$ in the HPIs increased at least four fold compared with the conventional polyimide membranes depending on the polymer structures. Based on these results, the polymer membranes modified with -OH groups in the polymer backbone showed favorable gas permeation and separation performance.

• Membrane Journal
• /
• v.11 no.4
• /
• pp.161-169
• /
• 2001

Single and mixed particle suspensions of kaolin, bentonite, starch and PMMA were carried out using a dead-end Amicon fi1tration cell with microfilteration membranes. The experimental data of permeate fluxes were fitted by the constant pressure fi1tration models in order to investigate fouling steps. In 0.1 wt% mixed solution of equal amount of kaolin and starch, the permeation flux was about 30% lower than the average of each particle flux. However, the permeation flux for kaolin/PMMA mixed solution was about 10% higher than the average of each particle flux. In the cases of bentonite and PMMA or starch mired solution, the improvement effect on permeation flux was weaken than that of kaolin mixed solution. Also, the membrane fouling resistance for mixed particle solution of equal amount of kaolin and starch was minimum at 0.05 wt% particle concentration.

• Journal of Pharmaceutical Investigation
• /
• v.24 no.2
• /
• pp.57-65
• /
• 1994

To increase the dissolution rate of practically insoluble biphenyl dimethyl dicarboxylate (DDB), various solid dispersions were prepared with water soluble carriers, such as povidone (PVP K-30), poloxamer 407, sodium deoxycholate (SDC) and polyethylene glycol (PEG) 6000, at drug to carrier ratios of 1:3, 1:5 and 1:10 (w/w) by solvent or fusion method. Dissolution test was performed by the paddle method. The dissolution rate of DDB tablets (25 mg) on market was found to be very low (11.44, 9.02 and 6.42% at pH 1.2, 4.0 and 6.5 after 120 min, respectively). However, dissolution rates of DDB from various solid dispersions were very fast and reached supersaturation within 10 min. DDB-PEG 6000 solid dispersion appeared to be better in enhancing the in vitro dissolution rate than others. Furthermore, the incorporation of DDB and phosphatidylcholine (PC) into ${\beta}-cyclodextrin$ at ratios of 1:2:20, 1:5:20 and 1:10:20 resulted in a 4.9-, 11.2- and 19.6-fold increase in DDB dissolution after 120 min as compared with the pure drug, respectively. This might be attributed to the formation of lipid vesicles which entrapped a certain concentration of DDB during dissolution. On the other hand, the permeation of DDB through rabbit duodenal mucosa was examined using some enhancers such as SDC, sod. glycocholate (SGC) and glycyrrhizic acid ammonium salt (GAA). Only trace amounts of DDB were found to permeate through deuodenal mucosa in the absence of enhancer. SDC was found to markedly decrease the permeation flux of DDB, however, SGC and GAA (5 mM) enhanced the flux of DDB 1.6 and 2.4 times higher as compared with no additive, respectively.

• Applied Chemistry for Engineering
• /
• v.10 no.8
• /
• pp.1099-1103
• /
• 1999

The surface of an ${\alpha}$-alumina tube was coated with zirconium modified polycarbosilane(PZC) by dip-coating method. Then the tube was pyrolyzed at 573~823 K. The prepared inorganic composite membrane was in $1{\mu}m$ thickness and had no pinholes larger than several nm. For the pyrolyzed inorganic composite membrane, the permeation test of He, $N_2$, $CO_2$, and $O_2$ was performed at 303~423 K. The gas permeation and separation factor were increased with increasing permeation temperature. The permeation for gases was controlled by the activated diffusion mechanism. The separation factor of $CO_2$, to $N_2$was 4.9 at 363 K on the composite membrane pyrolyzed at 823 K and its value was higher than that of He and $O_2$.

• Applied Chemistry for Engineering
• /
• v.10 no.2
• /
• pp.319-323
• /
• 1999

Asymmetric polyetherimide membranes were prepared by phase inversion method. In the modification of the skin layers of polyetherimide membranes, the effects of NaOH concentration on the morphology and pervaporation separation of water-isopropanol mixtures were investigated. With increasing concentration of NaOH solution, polyamicacid structure was formed by the hydrolysis of imide group of polyetherimide, and the thickness of dense layer of the asymmetric membrane increased. In the pervaporation separation of water-isopropanol mixtures the overall permeation rate decreased and the separation factor increased with increasing concentration of NaOH solution. However, when the concentration of NaOH solution was very high, the permeation rate increased but separation factor decreased. From these results, it was found that the permeation behaviors of asymmetric polyetherimide membranes depended upon the concentration of NaOH solution. These modified membranes showed that both the permeation rate and separation factor increased as the operating temperature increased.

• Membrane Journal
• /
• v.8 no.2
• /
• pp.86-93
• /
• 1998

A permeation apparatus has been devdoped which could make the on-line measurements of both flux and permeate composition. Pervaporative experiment of a single component, i.e. water was performed by using poly(vinyl alcohol) membrane crosslinked with glutaraldehyde to confirm the validity of the apparatus. In the experiment, steady-state permeation was obtained in 15 minutes and the measurement could be completed within 20 minutes. A comparison of the on-line measurement was made with the fluxes measured simultaneously by the conventional method in which the permeates were collected by liquid nitrogen. The on-line measurement by the apparatus showed an excellent agreement with the conventional measurement within a difference of $\pm$2%. From the flux data with operating time, 3 kinds of diffusion coefficients of water $D_{slope}, D_{1/2}$, and $D_t$ were determined, which were also coincident with values in a literature. It was confirmed that accurate measurements of fluxes could be obtained from the apparatus.