• The Journal of Engineering Geology
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• v.24 no.4
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• pp.583-595
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• 2014

The chemical properties and composition (pH, CaO, Fe, $HCO{_3}^-$, and $SO{_4}^{2-}$) of groundwater (GW) and surface water (SW) from the northern (non-carbonate bedrock) and southern (carbonate bedrock) sections of the Daedong River, Pyeongyang were analyzed and compared period of the 1930s. In the southern section, the GW and SW has a higher pH and $SO{_4}^{2-}$ concentration, but lower $HCO{_3}^-$ and Fe levels than in the north. This finding reflects a reaction that formed acid by replacing metal ions in inorganic salts by hydrogen, which resulted from the oxidation of organic material in a clay layer.

• Membrane Journal
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• v.25 no.3
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• pp.256-267
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• 2015

The goal is to compare two different aeration strategies for a pilot scale operation of submerged microfiltration with respect to the minimization of membrane fouling. A constant aeration (65 L/min) was examined parallel with a step-wise increase in airflow rate (40 to 65 L/min). The airflow rate was stepped to a higher rate every 5 min and the step-aeration cycles were repeated at regular intervals of 15 min. The comparative filtration runs were conducted with synthetic water containing powdered activated carbon (~10 g/L) and/or kaolin (~20 g/L) at a constant flux of 80 LMH. The extent and mechanisms of fouling in the microfiltration were identified by determining hydraulic resistance to filtration and the fouling reversibility after cleaning. Results showed that the step-aeration effectively alleviated fouling in the microfiltration of synthetic water compared to when using constant aeration. A substantial decrease in fouling was achieved by combining with coagulation using aluminum salts regardless of the aeration strategies. The constant aeration resulted in increased pore blocking likely due to increased accumulation of particles on the surface of membrane.

• Membrane Journal
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• v.30 no.3
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• pp.149-157
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• 2020

Ionic Liquid (IL) in the category of low-temperature molten salts with organic cation and organic/inorganic anion has shown great potentiality in CO₂ gas separation. CO₂ gas separation from flue gas by IL based membrane has been widely researched in recent years to overcome climate change and global warming. Membranes based on free standing polyionic liquid (PIL), blend of ionic liquid and composite ionic liquid membranes are discussed in this review. Introducing different IL monomers and tuning microstructure of PIL membrane and composite of PIL-IL to enhance mechanical properties of membranes with good CO₂ gas permeability and selectivity. Variations in cation and anions of monomer has great impact on the membrane gas separation performance.

• Membrane Journal
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• v.24 no.6
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• pp.472-483
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• 2014

This study is preparation of microporous membranes by using macrocyclic metal ion complexes and extended cage complexes. It is a more favorable way to existing methods because polymer and metal ion-ligand complex system provides a fine control over the phase transition behavior. Chemical functionalization of the polar surface can be obtained. Metal-templated condensation of cyclohexanedione dioxime, hydroxyphenylboronic acid in the presence of metal salts proceeds cleanly in methanol to furnish the metal clathrochelate complexes. Organic/inorganic hybrid membranes were prepared with polyethersulfone (PES), polyvinylpyrrolidone (PVP), ethyleneglycol butyl ether (BE), metal clathrochelate s and DMF by using nonsolvent induced phase inversion method. The structure of membranes was characterized with scanning electron microscopy (SEM) and microflow permporometer. The addition of Fe(II) clathrochelate complex with p-hydroxyphenyl group leads to changes of membrane morphology such as narrow mean pore size distribution, increase of surface pore density and decrease of the largest pore size.

• Microbiology and Biotechnology Letters
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• v.15 no.2
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• pp.135-139
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• 1987

Aspergillus sp. MK-24 was cultured at 3$0^{\circ}C$ in the medium consisting of 2% glucose, 0.2% NaNO$_3$, 0.02% $K_2$HPO$_4$, 0.02% MgSO$_4$ 7$H_2O$, 0.02% KCl, and at initial pH of 5.0. The production of the inhibitor on venom proteinase reached to the maximum in 7 days. Sodium nitrate or potassium nitrate as a nitrogen source was favorable. The production of inhibitor was not affected by the addition of most of the inorganic salt used but depressed by lead, zinc, cobalt, mercuric or silver salts.

• Journal of the Korean Chemical Society
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• v.40 no.3
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• pp.173-179
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• 1996

Transmission Electron Microscopy (TEM) was used to monitor the response of vesicle size and the intervesicle agglomeration with a variety of experimental parameters. Considered parameters are: (a) reaction temperture, (b) concentration of phosphatidylcholine, (c) concentration of aluminum ion with fixed concentration of phosphatidylcholine at 0.39 mM, and (d) mixed concentration of aluminum and phosphatidylcholine when fixing the weight ratio of phosphatidylcholine to aluminum at 0.01. Controlling these parameters, vesicle size changed and intervesicle agglomeration observed. As reaction temperature and the concentration of phosphatidylcholine increase, vesicle size decreases. With 0.2 M of aluminum ion, abnormal vesicle growth led by intervesicle agglomeration and coalescence was observed. When weight ratio of phosphatidylcholine to aluminum is 0.01, optimal vesicle size and size distribution can be obtained.

• KSBB Journal
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• v.11 no.6
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• pp.636-641
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• 1996

The production of extracellular mannitol by a new mannitol-producing bacterium, Leuconostoc sp. KY-002 was studied in shake flask cultures. The new isolate has a capability of utilizing fructose and sucrose for mannitol formation. Maximum mannitol production was obtained with fructose as the sole carbon source. Under the optimal culture conditions, within 70 hours of incubation, a final concentration of 26 g/L of mannitol from 50 g/L fructose was obtained with an indicated yield of 52% based on fructose consumed. However, higher concentrations of fructose ranging from 100 to 250 g/L could not effectively be transformed to mannitol due to a lack of osmotolerance. The strain produced no other polyols such as glycerol and sorbitol as by-products. Yeast extract was the best nitrogen source and high levels of inorganic phosphate up to 10 g/L promoted mannitol formation. Any mineral ions and salts did not play important role in both cell growth and mannitol production. Nicotinic acid enhanced mannitol production by 16%. The optimum culture temperature and initial pH were $35^{\circ}C$ and 6, respectively.

• Journal of the Korean Chemical Society
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• v.32 no.4
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• pp.333-341
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• 1988

The bio-electrode for cytosine has been constructed by immobilizing Proteus mirabilis and Citrobacter freundii on an ammonia gas-sensor. Bacteria containing cytosine deaminase convert one molecule of cytosine into one molecule of ammonia. The Proteus mirabilis bacterial electrode showed linear response to cytosine concentration in the $1.0{\times}10^{-3}\;-\;5.0{\times}10^{-2}$M with a slope of 45-48 mV/decade in 0.2 M phospbate buffer solution at pH 8.4. The Citrobacter freundii bacterial electrode showed linear response to cytosine concentration in the $7.0{\times}10^{-5}\;-\;7.0{\times}10^{-3}$M with a slope of 48 mV/decade in 0.05M phosphate buffer solution at pH 7.6. These electrode were investigated for the effects of pH, temperature, buffer solutions, amounts of bacteria, interferences, inorganic salts and lifetime.

• The Korean Journal of Mycology
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• v.12 no.4
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• pp.129-132
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• 1984

To find antitumor constituents in Korean basidiomycetes, the mycelia of Lentinus edodes DMC7, which had shown a good mycelial growth in shakeflasks, were cultured at $27^{\circ}C$ on an orbital shaking incubator at 180 rev/min for 12 days. The medium was composed of glucose (50g/l), yeast extract (9g/l), peptone (9g/l), and seven inorganic salts. A water soluble macromolecular fraction, LF-3, was obtained from the culure filtrate by fractionation with ethanol and dialysis using a Visking tube. When LF-3 was administered i.p. at 50mg/kg/day once daily for 10 consecutive days to female ICR mice which were implanted s.c. with sarcoma 180 $(10^6\;cells/mouse)$, it exerted a highly significant antitumor activity, with the tumor inhibition ratio of 53. 1%.

• Applied Biological Chemistry
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• v.23 no.4
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• pp.211-217
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• 1980

Using Streptomyces chibaensis, which produces a strong inulin-hydrolyzing enzyme, the optimum cultural conditions and composition of the medium for the production of inulase were studied. 1. The highest enzyme activity was obtained at pH 7.5 after 84 hours culture at $30^{\circ}C$. 2. None of carbon source better than inulin was found. 3. $(NH_4)_2HPO_4$ and corn steep liquor were favourable inorganic and organic nitrogen sources for the production of inulase. 4. $KCl,\;MgSO_4\;and\;FeSO_4$ as the metallic salts were effective for the enzyme production at their concentrations of 0.01, 0.05 and 0.0001%, respectively. 5. The highest production of inulase was obtained from the medium of inulin 1.0% and corn steep liquor 2.0% concentrations, respectively.