• Membrane and Water Treatment
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• v.2 no.3
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• pp.147-158
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• 2011

Membrane distillation process was used for desalination of hot (333 K) geothermal water, which was applied in the plant producing heating water. The investigated water contained 120 g salts/$dm^3$, mainly NaCl. The mineral composition was studied using an ion chromatography method. The obtained rejection of solutes was closed to 100%, but the small amounts of $NH_3$ also diffused through the membrane together with water vapour. However, the composition of obtained distillate allowed to use it as a makeup water in the heating water system. The geothermal water under study was concentrated from 120 to 286 g NaCl/$dm^3$. This increase in the solution concentration caused the permeate flux decline by a 10-20%. The geothermal water contained sulphates, which was subjected to two-fold concentration to achieve the concentration 2.4-2.6 g $SO{_4}{^{2-}}/dm^3$ and the sulphates then crystallized in the form of calcium sulphate. As a results, an intensive membranes scaling and the permeate flux decline was observed. The XRD analysis indicated that beside the gypsum also the NaCl crystallites were deposited on the membrane surfaces. The fresh geothermal water dissolved the mixed $CaSO_4$ and NaCl deposit from the membrane surface. This property can be utilized for self-cleaning of MD modules. Using a batch feeding of MD installation, the concentration of geothermal water was carried out over 800 h, without significant performance losses.

• Membrane and Water Treatment
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• v.11 no.2
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• pp.159-166
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• 2020

In this study, the performance and antifouling properties of polysulfone (PSf) and polyvinylidene fluoride/polyvinylpyrrolidone (PVDF/PVP) membranes in a membrane bioreactor (MBR) were investigated. The membranes were prepared via phase inversion method, and then characterized by a set of analyses including contact angle, porosity and water flux and applied in a lab-scale MBR system. Soluble microbial product (SMP), extracellular polymeric substance (EPS), FTIR, gel permission chromatography (GPC) and particle size distribution (PSD) analyses were also carried out for MBR system. The results showed that the MBR with PSf membrane had higher hydrophobic organic compounds which resulted in formation of larger flocs in MBR. However, in this MBR had high compressibility coefficient of cake layer was higher (n=0.91) compared to MBR with PVDF/PVP membrane (n=0.8); hence, the fouling was more profound. GPC analysis revealed that compounds with molecular weight lower than 2 kDa are more formed on PSf membrane more than PVDF/PVP membrane. The results of FTIR analysis confirmed the presence of polysaccharide and protein compounds on the cake layer of both membranes which was in good agreement with EPS analysis. In addition, the results showed that their concentration was higher for the cake on PSf membrane.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2290-2295
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• 2018

An acceleration stress test (AST) was performed to evaluate the durability of a polymer membrane in a polymer electrolyte membrane fuel cell (PEMFC) for 500 hours. Previous studies have shown that hydrogen crossover measured by linear sweep voltammetry (LSV) increases when the polymer membrane deteriorates in the AST process. On the other hand, hydrogen crossover of the membrane often decreases in the early stages of the AST test. To investigate the cause of this phenomenon, we analyzed the MEA operated for 50 hours using the AST method (OCV, RH 30% and $90^{\circ}C$). Cyclic voltammetry and transmission electron showed that the electrochemical surface area (ECSA) decreased due to the growth of electrode catalyst particles and that the hydrogen crossover current density measured by LSV could be reduced. Fourier transform infrared spectroscopy and thermogravimetric/differential thermal analysis showed that -S-O-S- crosslinking occurred in the polymer after the 50 hour AST. Gas chromatography showed that the hydrogen permeability was decreased by -S-O-S- crosslinking. The reduction of the hydrogen crossover current density measured by LSV in the early stages of AST could be caused by both reduction of the electrochemical surface area of the electrode catalyst and -S-O-S- crosslinking.

• Microbiology and Biotechnology Letters
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• v.22 no.1
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• pp.1-6
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• 1994

We have studied the relation between Ca$^{2+}$-ATPase and trigger peptidase(TPase) which are membeane protein well known as their significant role for signal transduction of mating pheromone in heterobasidiomycetous yeast. Rhodosporidium toruloides. We found out that there were Ca $^{2+}$-ATPase and TPase together in isolated calmodulim binding protein(CBP), usion calmodulin affinity column chromatography after solubilization of mation type a cell membrane protein, and that the dependence of enzyme activity of both the enzymes on Ca$^{2+}$, phospholipid and nonionic detergent are similar. However, Ca$^{2+}$-ATPase hed quite absolute dependence on calmodulin and, on the other hand, TPase didn't have any dependence. Judging from the fact that there are both enzymes in CBP which the dependence of calmodulin are quite different, we found out that both enzymes were made to their compound and existed in mating type a cell membrane.

• Membrane Journal
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• v.29 no.3
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• pp.183-189
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• 2019

Amphiphilic PCZ-r-PEG random copolymer assisted solvothermal process is used to prepare mesoporous $TiO_2$ microspheres generated from nanoparticles by self-assembly method. Synthesized PCZ-r-PEG is characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC) and transmission electron microscopy (TEM). The mesoporous $TiO_2$ are prepared by PCZ-r-PEG, glucose, water in tertrahydrofuran solution at $150^{\circ}C$ for 12 h and the $TiO_2$ microspheres are calcined at $550^{\circ}C$ for 30 min to further crystallize and organic residue are removed. Morphology and crystallization phase is characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. The mesoporous $TiO_2$ crystallized in pure anatase phase with diameter of $300{\pm}20nm$.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.845-851
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• 2008

TolC is an outer membrane porin protein and an essential component of drug efflux and type-I secretion systems in Gram-negative bacteria. TolC comprises a periplasmic $\alpha$-helical barrel domain and a membrane-embedded $\beta$-barrel domain. TdeA, a functional and structural homolog of TolC, is required for toxin and drug export in the pathogenic oral bacterium Actinobacillus actinomycetemcomitans. Here, we report the expression of the periplasmic domain of TdeA as a soluble protein by substitution of the membrane-embedded domain with short linkers, which enabled us to purify the protein in the absence of detergent. We confirmed the structural integrity of the TdeA periplasmic domain by size-exclusion chromatography, circular dichroism spectroscopy, and electron microscopy, which together showed that the periplasmic domain of the TolC protein family fold correctly on its own. We further demonstrated that the periplasmic domain of TdeA interacts with peptidoglycans of the bacterial cell wall, which supports the idea that completely folded TolC family proteins traverse the peptidoglycan layer to interact with inner membrane transporters.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.7
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• pp.492-497
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• 2014

This study investigated removal characteristics of organic matters in pretreatment and reverse osmosis (RO) membrane processes for seawater desalination. Also, the influence of the changes in characteristics of organic matters on the membrane fouling was assessed. The pretreatment processes included dual media filtration (DMF), pressurized membrane filtration (MF), and submerged membrane filtration (SMF). Turbidity, UV absorption at 254 nm, dissolved organic carbon, size exclusion chromatography (SEC), fluorescence excitation emission matrix (FEEM), and transparent exopolymer particles (TEP) in raw and processed waters were analyzed. Ions and minerals were not removed by any pretreatment process tested, but were removed over 99% through the RO membrane process. Hydrophobic organics, which can play major role in organic membrane fouling, were relatively readily removed compared with hydrophilic ones. Membrane based pretreatment such as MF and SMF exhibited better removals of organics than conventional DMF. As the levels of organics in pretreated water decreased, the silt density index (SDI) decreased. MF treated water exhibited the lowest SDI value; this is possibly due to the lowest TEP ($0.1-0.4{\mu}m$) concentrations.

• Journal of Environmental Health Sciences
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• v.16 no.2
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• pp.113-119
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• 1990

Many studies on the analysis of cations in blood have been reported. However, no suitable method for the pretreatment of blood for the determination of cations by Ion Chromotography. As a result, pretreatment method that the membrane filtration of plasma a diluted 1 to 100 fold acidified pH 3.5 was found to be the most suitable. The recoveris of monovalent cations in blood were yield 101%(Na$^{+}$). 102%(NH$^{+}_{4}$) and 101%(K$^{+}$) Determinations of divalent cations(Mg and Ca ions) in blood by Ion chromatography were summarized as followed conditions Separator Column : CS$_{3}$. Suppressor Column : CMMS. Eluent conen : 25m M-HCl/2mM-Histidine. Regenerant conen: 40mM-Ba(OH)$_{2}$.

• Journal of Environmental Health Sciences
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• v.17 no.1
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• pp.89-94
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• 1991

There are many pretreatment and detection methods for divalent cations in blood. But our purpose was to study the pretreatment of blood for the determination of cations by Ion Chromatography. We compared with recovery of Mg$^{++}$, and Ca$^{++}$ contained in plasma according to four pretreatment methods, that is, add of trichloroacetic acid and perchloric acid, dilution with distilled water and membrane filter method. As a result, add of trichloroacetic acid was found to be the most suitable method for good recovery of Mg$^{++}$ (98.0%) and Ca$^{++}$(96.0%) in plasma, and the Mg$^{++}$ and Ca$^{++}$ contents in plasma was 20 and 102 ($\mu$g/ml)

• Preventive Nutrition and Food Science
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• v.8 no.1
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• pp.66-69
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• 2003

An angiotensin converting enzyme (ACE) inhibitory peptide was isolated and purified from the hydrolysates of duck meat protein. Duck meat protein was hydrolyzed using trypsin at 37$^{\circ}C$ for 2 hrs. An ACE inhibitory peptide was purified using membrane filtration, anion exchange chromatography, gel permeation chromatography, fast protein liquid chromatography, normal phase HPLC. The purified inhibitory peptide was identified to be a tetrapeptide, Glu-Asp-Leu-Glu having $IC_{50}$/ value of 85.9 $\mu$M.