• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.662-669
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• 2011

This study was conducted to biologically convert methane into methanol. Methane contained in biogas was bio-catalytically oxidized by methane monooxygenase (MMO) of methanotrophs, while methanol conversion was observed by inhibiting methanol dehydrogenase (MDH) using MDH activity inhibitors such as phosphate, NaCl, $NH_4Cl$, and EDTA. The degree of methane oxidation by methanotrophs was the most highly accomplished as 0.56 mmol for the condition at $35^{\circ}C$ and pH 7 under 0.4 (v/v%) of biogas ($CH_4$ 50%, $CO_2$ 50%) / Air ratio. By the inhibition of 40 mM of phosphate, 50 mM of NaCl, 40 mM of $NH_4Cl$ and $150{\mu}m$ of EDTA, methane oxidation rate could achieve more than 80% regardless of type of inhibitors. In the meantime, addition of 40 mM of phosphate, 100 mM of NaCl, 40 mM of $NH_4Cl$ and $50{\mu}m$ of EDTA each led to generating the highest amount of methanol, i.e, 0.71, 0.60, 0.66, and 0.66 mmol when 1.3, 0.67, 0.74, and 1.3 mmol of methane was each concurrently consumed. At that time, methanol conversion rate was 54.7, 89.9, 89.6, and 47.8% respectively, and maximum methanol production rate was $7.4{\mu}mol/mg{\cdot}h$. From this, it was decided that the methanol production could be maximized as 89.9% when MDH activity was specifically inhibited into the typical level of 35% for the inhibitor of concern.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.148-158
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• 2019

The corrosion protection of AA2024 PPy coated samples doping with nanosized metal oxides, including $TiO_2$ and $CeO_2$ nanoparticles and $Nd_2O_3$ nanorods, during exposure to the solutions of 0.1 M $H_2SO_4$ and 3.5% NaCl was evaluated by electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques. The nanorods of $Nd_2O_3$ were synthesized by cathodic pulse electrochemical deposition technique. The barrier properties of the different PPy coatings containing nanosized metal oxides immersed in $H_2SO_4$ solution were ranked as follows: $Nd_2O_3$ > $TiO_2$ > $CeO_2$. Therefore, the $Nd_2O_3$ coating sample provided the highest corrosion protection at any time of immersion up to 72 hours after immersing in $H_2SO_4$ solution. On the other hand, the $CeO_2$ coating sample displayed the best anticorrosive properties among the other coating samples after immersion in NaCl solution up to 28 days. This is due to the inhibition effect of cerium ions on aluminum alloys at near-neutral solutions.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.84-88
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• 2001

About 100 bacterial strains producing proteolytic enzymes were isolated from Korean traditional soy paste Doenjang. Among them, strain SYG3 producing the highest level of angiotensin converting enzyme (ACE) inhibitor into the culture medium was selected and identified as Bacillus pumilus according to the Bergey's mannual of systematic bacteriology. Soybean powder as a nitrogen source and glucose as a carbon source supported high level of ACE inhibitor production. The presence of 3% NaCl also enhanced the production of ACE inhibitor in the medium. The optimum initial pH of the medium and culture temperature for the production of ACE inhibitor were 7.0 and $32^{\circ}C$, respectively. The maximal level of ACE inhibitory effect was obtained after 36 hours of cultivation under the optimized conditions, which was about 98% of inhibition ratio.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.5
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• pp.782-786
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• 2001

The taste characteristics and functionality of low-utilized small longfinned squid as affected by two stage enzyme hydrolysis were examined. In taste active-components, total free amino acid contents in hot-water and autolytic extract, two stage enzyme hydrolysate (TSEH) of longfinned squid were 2,792.5 mg%, 8,393.8 mg% and 9,186.1 mg%, respectively. The major free amino acids were Pro, Leu, Glu, Tau, Lys, Arg, Phe, Val and Ile. As for quarternary ammonium bases, betaine was the principal component (593.8 mg%) and also contents of TMAO, AMP in longfinned squid TSEH were 234.8% mg% and 51.0 mg%, respectively. The major inorganic ions in TSEH were Na(874.0 mg%), K (398.2 mg%), Cl (1,213.1 mg%) and PO$_4$(995.9 mg%). From the results in sensory tests, TSEH was superior to other extracts on the aspects of taste characteristics such as umami intensity, sweetness, taste harmony and transparency of extract. Also TSEH of longfinned squid revealed very higher Angiotensin-I converting enzyme inhibition ratio (92.1%) than those of hot-water and autolytic extract.

• The Korean Journal of Physiology
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• v.30 no.2
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• pp.197-208
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• 1996

Endosomes lower their internal pH by an ATP-driven proton pump, which is critical to dissociation of many receptor-ligand complexes, the first step in the intracellular sorting of internalized receptors and ligands. Endosomes are known to exhibit n great range of pH values that can vary between 5.0 and 7.0 within a single cell although the factors that regulate endosomal pH remain uncertain. To evaluate the morphological and topological differences of endosomes in the different stages, confocal microscopy was used. The early endosomes labeled with fluorescein isothiocyanate-dextran for 10 min at $37^{\circ}C$ were identifiable at the peripheral and tubule-vesicular endosome compartment. In contrast, the late endosomes formed by 10 min pulse and 20 min trace were located deeper in the cytoplasm and showed more vesicular features than early endosomes. For the purpose of determining whether ATP-dependent acidification was heterogeneous and whether the differences in acidification were attributed to differences in the activity of $Na^{+}-K^{+}$-ATPase and/or $Cl^{-}$ channel, endocytic compartments were fractionated into subpopulation using percoll gradient and measured ATP-dependent acidification. While all fractions exhibited ATP-dependent acidification activity, both the initial rate of acidification and extent of proton translocation were lower in early endosomes and gradually increased in late endosomes. Phosphorylation by PKA and ATP enhanced ATP-dependent acidification in both early and late endosomes, hut there was no difference in the degree of enhancement by phosphorylation between two subpopulations. When ATP-dependent acidification was determined in the presence or absence of vanadate ($Na_{3}VO_{4}$) or ouabain, only early endosomes exhibited the vanadate or ouabain dependent stimulation of acidification activity, suggesting the inhibition of $Na^{+}-K^{+}$-ATPase. Therefore, it seems probable that the inhibition of early endosome acidification by $Na^{+}-K^{+}$-ATPase observed in vitro at least in part plays a physiological role in controlling the acidification of early endosomes in vivo.

• Journal of Plant Biotechnology
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• v.34 no.1
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• pp.61-68
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• 2007

To develop rice (Oryza sativa L.) cultivars to be planted on salt-affected sites, cell lines with enhanced proline content and resistance to growth inhibition by Azetidine-2-carboxylic acid (AZCA), a proline analogue, were screened out among calli irradiated with gamma ray of 50, 70, 90, and 120 Gy. The calli had been derived from embryo culture of the cultivar Donganbyeo. Selected AZCA resistant lines that had high proline accumulation were used as sources for selection of NaCl resistant lines. To determine an optimum concentration for selection of NaCl resistant lines, Donganbyeo seeds were initially cultured on the media containing various NaCl concentrations (0 to 2.5%) for 40 days, and 1.5% NaCl concentration was determined as the optimum concentration. One hundred sixteen salt-tolerant (ST) lines were selected from bulked 20,000 seeds of the AZCA resistant $M_{3}$ seeds in the medium containing 1.5% NaCl. The putative 33 lines ($M_{4}$ generation) considered with salt-tolerance were further analyzed for salt tolerance, amino acid and ion contents, and expression patterns of the salt tolerance-related genes. Out of the 33 lines, 7 lines were confirmed to have superior salt tolerance. Based on growth comparison of the entries, the selected mutant lines exhibited greater shoot length with average 1.5 times, root length with 1.3 times, root numbers with 1.1 times, and fresh weight with 1.5 times than control. Proline contents were increased maximum 20%, 100% and 20% in the leaf, seed and callus, respectively, of the selected lines. Compared to control, amino acid contents of the mutants were 24 to 29%, 49 to 143%, 32 to 60% higher in the leaf, seed and callus, respectively. The ratio of $Na^{+}/K^{+}$ for most of the ST-lines were lower than that of control, ranging from 1.0 to 3.8 for the leaf and 11.5 to 28.5 for the root, while the control had 3.5 and 32.9 in the leaf and root, respectively. The transcription patterns for the P5CS and NHXI genes observed by RT-PCR analysis indicated that these genes were actively expressed under salt stress. The selected mutants will be useful for the development of rice cultivar resistant to salt stress.

• Korean Journal of Microbiology
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• v.25 no.3
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• pp.249-253
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• 1987

Effects of Ac pulse at low voltage on Saccharomyces cerevisiae were studied. The treatment of yeast suspensions contained 0.2m NaCl with 500mA for 350 sec at $40^{\circ}C$ was shown about 50% of lethality, whereas in the treatment of the same suspensions with 250mA for 250 sec at the temperature ($10^{\circ}C$) corresponding to about 10% of lethality, growth was completely inhibited instead of lethality. The effect of growth inhibition was due to occurrence of auxotrophic strains under experimental conditions. Detection of auxotrophic yeasts was done tentatively with the difference of the number of viable yeast cells between direct counting by methylene blue staining and plate-count on yeast morphology agar.

• Journal of Electrochemical Science and Technology
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• v.12 no.3
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• pp.308-316
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• 2021

In this work, we report synthesis, characterization and corrosion inhibition properties of cationic thiol surfactant-capped silver (SC-Ag-NPs) and gold (SC-Au-NPs) nanoparticles. SC-Ag-NPs and SC-Au-NPs were characterized using regular techniques include TEM. Corrosion study was carried out using carbon steel (CS) in 3.5% NaCl aqueous solution and characterized using multiple electrochemical techniques. Our results suggest that the paint containing SC-Ag-NPs and SC-Au-NPs endow efficient corrosion protection to the CS. Especially, SC-Au-NPs based paint form a stronger barrier between the metal and the corrosive ions, leading to better inhibition properties.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.121-122
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• 2023

This study investigates the anti-corrosion properties of two eco-friendly pyridinium ionic liquids; 4DMN and 4DMP, in a 3.5% NaCl solution. Utilizing weight loss tests, EIS, PDP, quantum chemical calculations, and molecular dynamics simulations, the study demonstrates concentration-dependent inhibition efficiencies of 94% and 92% for 4DMN and 4DMP, respectively. The compounds modulate both anodic and cathodic reactions without altering the corrosion mechanism. EIS data suggest that a protective layer forms, supported by FE-SEM and AFM surface analyses, which reveal improved morphology and reduced roughness. Computational validations corroborate these empirical findings, highlighting the feasibility of these ionic liquids for effective, sustainable corrosion mitigation.

• Journal of the Korean GEO-environmental Society
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• v.13 no.4
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• pp.5-11
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• 2012

Acid mine drainage (AMD) is one of the most severe environmental problem that results from the oxidation of pyrite $(FeS_2)$ and various other metal sulfides. In this study, the influence of microorganism was tested on the process where AMD was released and the method to inhibit AMD generated by microorganisms at abandoned mine area. The activity and growth rate of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, common microorganisms affecting AMD occurrence, were measured. Chlorine dioxide $(ClO_2)$, NaCl, or surfactant (ASOR-770) was used as an inhibitor for working on activity and growth of microorganism. Among the three inhibitors, 10ppm of chlorine dioxide was the most effective inhibitor for AMD control due to the reduced the activity and growth of microorganisms by 20%.