• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.156-163
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• 2018

High-performance mixed-matrix membranes that comprise both zeolitic imidazolate framework-8 (ZIF-8) and graphene oxide (GO) were synthesized with a solution casting technique to realize excellent $CO_2/CH_4$ separation. The incorporation of ZIF-8 nanocrystals alone in ODPA-TMPDA polyimide can be used to significantly enhance $CO_2$ permeability compared with that of pure ODPA-TMPDA. Meanwhile, the addition of a GO nanostack alone in ODPA-TMPDA contributes to improved $CO_2/CH_4$ selectivity. Hence, a composite membrane that contains both fillers displays significant enhancements in $CO_2$ permeability (up to 60%) and $CO_2/CH_4$ selectivity (up to 28%) compared with those of pure polymeric membrane. Furthermore, in contrast to the ZIF-8 mixed-matrix membrane, which showed decreased mechanical stability, it was found that the incorporation of GO could improve the mechanical strength of mixed-matrix membranes. Overall, the synergistic effects of the use of both fillers together are successfully demonstrated in this paper. Such significant improvements in the mixed-matrix membrane's $CO_2/CH_4$ separation performance and mechanical strength suggest a feasible and effective approach for potential biogas upgrading and natural gas purification.

• Korean Membrane Journal
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• v.5 no.1
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• pp.68-74
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• 2003

Methane steam reforming (MSR) reaction for hydrogen production was studied in a membrane reactor (MR) using two tubular membranes, one Pd-based and one of porous alumina. A higher methane conversion than the thermodynamic equilibrium for a traditional reactor (TR) was achieved using MRs. The experimental temperature range was 350-500$^{\circ}C$; no sweep-gas was employed during reaction tests to avoid its back-permeation through the membrane and the steam/methane molar feed ratio (m) varied in the range 3.5-5.9. The best results (the difference between the MR conversion and the thermodynamic equilibrium was of about 7%) were achieved with the alumina membrane, working with the highest steam/methane ratio and at 450$^{\circ}C$. Silica membranes prepared at KRICT laboratories were characterized with permeation tests on single gases (N$_2$, H$_2$ and CH$_4$). These membranes are suited for H$_2$ separation at high temperature.

• BMB Reports
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• v.29 no.4
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• pp.335-342
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• 1996

Porcine liver cysteinesulfinic acid decarboxylase was purified approximately 460-fold by means of ammonium sulfate fractionation and sequential column chromatographic separation with Sephadex G-100, DEAE-cellulose and hydroxylapatite. The enzyme has a flat pH profile with maximum activity occurring between pH 6.0 and 7.6. Pyridoxal 5'-phosphate must be present in all buffers used for purification procedures in order to stabilize the enzyme. Addition of sulfhydryl reagents such as 2-mercaptoethanol are also necessary to maintain maximum enzyme activity throughout purification. The absorption spectrum shows that cysteinesulfinic acid decarboxylase is a pyridoxal 5' -phosphate-containing protein. The major absorption is at 280 nm with two smaller absorption regions, one at 425 nm which is ascribed to a Schiffs base between pyridoxal phosphate and protein, and another at 325 nm which is thought to be due to the interaction of 2-mercaptoethanol with the Schiffs base. A number of divalent cations tested did not affect enzyme activity with the exception of mercury, copper, and zinc which are inhibitory. The partially purified enzyme has an apparent $K_m$ of 0.94 mM for cysteinesulfinate. Cysteic acid is a competitive inhibitor of the enzyme with a $K_i$ of 1.32 mM. The molecular weight of the enzyme was estimated to be about 79,600 by using Sephadex G-200 column chromatography.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.501-504
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• 2003

A novel prepurification method was developed aiming at increasing yield and purity, also reducing solvent usage for purification of paclitaxel. This method was a simple and efficient procedure, for the isolation and prepurification of paclitaxel from the biomass of Taxus chinensis, consisting of micelle formation, followed by two steps of precipitation. The use of a micelle and precipitation in the prepurification process allows for rapid separation of paclitaxel from interfering compounds and dramatically reduces solvent usage compared to alternative methodologies. This prepurification process serves to minimize the size and complexity of the HPLC operations for paclitaxel purification. This process is readily scalable to a pilot plant and eventually to a production environment where multikilogram quantities of material are expected to be produced. As much as possible, the process has been optimized to minimize solvent usage, complexity, and operating costs.

• Microbiology and Biotechnology Letters
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• v.31 no.2
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• pp.201-204
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• 2003

Glycopeptide antibiotics, teicoplanin was purified from a mutant strain of Actinoplanes teichomyceticus ATCC31121, A. teichomyceticus MSL2211. We developed a simple procedure to separate and purify the teicoplanin from the fermentation broth. Teicoplanin was purified by two-step purification system, hydrophobic adsorption and sugar affinity chromatography in combination with HPLC analysis based on the properties of hydrophobic acyl chain and sugar moiety in teicoplanin. Teicoplanin was separated from the culture broth by Diaion HP-20 and further purified by concanavalin A affinity column chromatography. As an adsorbent resin, Diaion HP-20 in broth eliminated toxic effects on growth, reduced feedback repression of teicoplanin production, and assisted In rapid recovery of teicoplanin. The teicoplanin displayed the final yield of 80% and 95% of purity.

• Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.191-195
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• 2012

We report here the use of high-speed countercurrent chromatography (HSCCC) in the preparative isolation and purification of the bioactive component, fucosterol, from Pelvetia siliquosa. A crude extract was obtained by ultrasonic extraction of powdered P. siliquosa using methylene chloride and was then subjected to separation and purification by HSCCC, coupled with evaporative light-scattering detection. Preparative HSCCC was performed successfully using a two-phase solvent system, n-heptane:methanol (3:2, v/v), to obtain 10.96 mg fucosterol with 96.8% purity from 50 mg of crude extract; the recovery rate was approximately 90.5%.

• KSBB Journal
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• v.8 no.3
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• pp.287-294
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• 1993

For the purpose of combining the purification processes for several biologically active proteins form human urine, an efficient integrated fractionation procedure has been investigated. The procedure was started by concentration with ultrafiltration and pH precipitation followed by a selectable combination of chromatography on gel filtration, adsorption, ion exchanger, affinity, and reverse phase column. By this process, the purified urokinase, epidermal growth factor and albumin migrated as a single band on SDS-polyacrylamide gel electrophoresis and were fully active. The recoveries of these purified proteins were 48%, 17%, and 46%, respectively.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.6
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• pp.395-401
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• 2001

Crystallins are a family of water-soluble proteins that constitute up to 90% of the wa-ter-soluble proteins in mammalian eye lenses, We present in this paper an alternative purification method for these proteins using polyethylene glycol/dextran aqueous two-phase extraction. Un-der the appropriate conditions, we were able to recover the γ-crystallin fraction essentially free of the remaining proteins. High concentrations of salt at a neutral pH maximize the recovery of γ-crystallins in the top phase and minimize the contamination by the other proteins present in the lenses. The proposed protocol decreases the separation time by about 50%. The complex partition behavior observed for these proteins reflects a delicate balance between protein/phase-forming species(various polymers and salts) and protein interactions. This is evidenced, in part, by the role played by the largest proteins in this group as a "pseudo"phase-forming species.

• Journal of Embryo Transfer
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• v.33 no.4
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• pp.327-336
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• 2018

To date, there are no protocols optimized to the effective separation of spermatogonial stem cells (SSCs) from testicular cells derived from mouse testes, thus hindering studies based on mouse SSCs. In this study, we aimed to determine the most efficient purification method for the isolation of SSCs from mouse testes among previously described techniques. Isolation of SSCs from testicular cells derived from mouse testes was conducted using four different techniques: differential plating (DP), magnetic-activated cell sorting (MACS) post-DP, MACS, and positive and negative selection double MACS. DP was performed for 1, 2, 4, 8, or 16 h, and MACS was performed using EpCAM ($MACS^{EpCAM}$), Thy1 ($MACS^{Thy1}$), or GFR ${\alpha}1$ ($MACS^{GFR{\alpha}1}$) antibodies. The purification efficiency of each method was analyzed by measuring the percentage of cells that stained positively for alkaline phosphatase. DP for 8 h, $MACS^{Thy1}$ post-DP for 8 h, $MACS^{GFR{\alpha}1}$, positive selection double $MACS^{GFR{\alpha}1/EpCAM}$, and negative selection double $MACS^{GFR{\alpha}1/{\alpha}-SMA}$ were identified as the optimal protocols for isolation of SSCs from mouse testicular cells. Comparison of the purification efficiencies of the optimized isolation protocols showed that, numerically, the highest purification efficiency was obtained using $MACS^{GFR{\alpha}1}$. Overall, our results indicate that $MACS^{GFR{\alpha}1}$ is an appropriate purification technique for the isolation of SSCs from mouse testicular cells.

• Membrane and Water Treatment
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• v.1 no.1
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• pp.1-12
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• 2010

Membrane distillation process was used for purification of pre-treated natural water (tap water). The rejection of inorganic and organic compounds in this process was investigated. The obtained rejection of inorganic solutes was closed to 100%, but the volatile organic compounds (VOCs) diffused through the membrane together with water vapour. The content of trihalomethanes (THMs) in the obtained distillate was two-three fold higher than that in the feed, therefore, the rejection of the total organic compounds present in the tap water was reduced to a level of 98%. The intensive membranes scaling was observed during the water separation. The morphology and composition of the fouling layer was studied using scanning electron microscopy coupled with energy dispersion spectrometry. The influence of thermal water pre-treatment performed in a heat exchanger followed by filtration on the MD process effectiveness was evaluated. This procedure caused that significantly smaller amounts of $CaCO_3$ crystallites were deposited on the membrane surface, and a high permeate flux was maintained over a period of 160 h.