• Journal of Korean Society of Water and Wastewater
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• v.13 no.1
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• pp.51-60
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• 1999

An intermittently-aerated, intermittently-decanted single-reactor process (KIDEA process : KIST intermittently decanted extended aeration process) was applied for nitrogen removal from wastewater. Synthetic wastewater with chemical oxygen demand (COD): nitrogen (N) ratio of approximately 5.25: 1 was used. The average COD removal efficiency reached above 95%, and under optimal conditions nitrogen removal efficiency also reached above 90%. This process consisted of 72 minute aeration, 48 minute settling and 24 minute effluent decanting with continuous feeding of influent wastewater from the bottom of the reactor, and did not require a separate anoxic mixing-phase. In this process, nitritation ($1^{st}$ step of nitrification) was induced but nitratation($2^{nd}$ step of nitrification) was suppressed. Main factors responsible for the accumulation of nitrite ion in the experimental condition were free ammonium and dissolved oxygen. This condition of nitrite build-up accelerated by continuous feed flow in the bottom of the KIDEA reactor because of high concentration of ammonia nitrogen in the influent. This research provides one of answers to control nitrate build-up.

• Journal of ILASS-Korea
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• v.24 no.1
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• pp.8-14
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• 2019

The purpose of this study is to develop a packing-free wet scrubber to prolong the maintenance interval compared with the conventional packed bed wet scrubbers with which frequent operation stops are unavoidable to clean the packing materials. The main- and interaction-effects were quantitatively analyzed by regression analysis for the measured ammonia scrubbing data from the experiments prepared by experimental design. The scrubbing efficiency of the newly developed wet scrubber was found to be over 95% under the condition of flue gas flow rate of 90CMM and liquid-to-gas ratio $2l/m^3$ for all considered trials of experimental design. The interaction effect between the inlet duct spray and the filter was found to be important, which controls the droplet growth due to the droplet collisions between the duct- and scrubbing tower-spray. The presented methodology to analyze the impacts of operational and design factors on the scrubber efficiency showed potential for applications to optimize the future flue gas abatement process in semiconductor plants.

• Journal of Microbiology and Biotechnology
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• v.29 no.5
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• pp.749-757
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• 2019

Nitrilase is a valuable hydrolase that catalyzes nitriles into carboxylic acid and ammonia. Its applications, however, are severely restricted by the harsh conditions of industrial reaction processes. To solve this problem, a nitrilase from Acidovorax facilis 72W was inserted into an Escherichia coli-Bacillus subtilis shuttle vector for spore surface display. Western blot, enzyme activity measurements and flow cytometric analysis results all indicated a successful spore surface display of the CotB-nit fusion protein. In addition, the optimal catalytic pH value and temperature of the displayed nitrilase were determined to be 7.0 and $50^{\circ}C$, respectively. Moreover, results of reusability tests revealed that 64% of the initial activity of the displayed nitrilase was still retained at the $10^{th}$ cycle. Furthermore, hydrolysis efficiency of upscale production of cyanocarboxylic acid was significantly higher in the displayed nitrilase-treated group than in the free group expressed by E. coli (pET-28a-nit). Generally, the display of A. facilis 72W nitrilase on the spore surface of Bacillus subtilis may be a useful method for immobilization of enzyme and consequent biocatalytic stabilization.

• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.883-889
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• 1988

The salted small shrimps(Acetes japonicus) were fermented for 3 months at room temperature. During the period of fermentation, the changes of shrimp protein properties were determined. The extractability of soluble protein was slightly decreased in 1 month fermentation, but thereafter increased. The contents of 10% TCA soluble fraction were gradually increased during 3 month fermentation, and the rate of 10% TCA soluble fraction/total soluble protein was also greatly increased during the period of fermentation. Sephadex G-100 gel filtration pattern was changed after 1 month fermentation, showing the disappearance of low molecular weight protein peaks, the decomposition and the delay of elution time of main shrimp protein peaks. Polyacrylamide gel disc electrophoresis patterns showed the degradation of main protein bands into lots of smaller bands after 1 month fermentation. The contents of total free amino acids were slightly decreased in 1 month fermentation and then gradually increased during the Period of fermentation. The rate of free amino acids/soluble protein was steadily increased during the period of fermentation, but the rate of free amino acids/10% TCA soluble fraction was decreased continually during the period of fermentation. The contents of most free amino acids were increased during the period of fermentation, but those of histidine and arginine were greatly decreased in 1 month fermentation. Ammonia was increased after 1 month fermentation. The pH value of salted shrimp was slowly changed during 3 months of fermentation, showing increase from 7.8 to 8.2.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.8
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• pp.1115-1120
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• 2002

The effects of seed-associated or free linseed oil on fermentation characteristics and long-chain unsaturated fatty acids composition, especially the formation of conjugated linoleic acid (CLA) and octadecenoic acid (trans-11 $C_{18:1}$, $t-C_{18:1}$) by mixed ruminal bacteria were examined in vitro. Concentrate (1% of culture solution, w/v, as-fed basis) with ground linseed (0.6% of culture solution, w/v, DM basis) or linseed oil as absorbed onto ground alfalfa hay was added to 600 ml mixed solution consisting of strained rumen fluid and artificial saliva at the ratio of 1:1 in a glass culture jar. The culture jar was covered with a glass lid with stirrer, and placed into a water-bath ($39^{\circ}C$) and incubated anaerobically up to 24 h. Seed-associated or free linseed oil did not significantly affect the pH and ammonia concentration in the culture solution. Molar percent of acetate tended to increase while that of propionate decreased with the addition of free oil treatment throughout the incubation. Differences in bacterial number were relatively small, regardless of the form of supplements. Decreasing trends in the compositions of linoleic acid ($C_{18:2}$) and linolenic acid ($C_{18:3}$) but increasing trends of stearic acid ($C_{18:0}$), $t-C_{18:1}$ and CLA compositions were found from culture contents up to 12h incubation when incubated with both ground linseed and linseed oil. The compositions of $C_{18:0}$, $C_{18:2}$ and $C_{18:3}$ were greater but those of oleic acid ($C_{18:1}$), $t-C_{18:1}$ and CLA were smaller in a culture solution containing ground linseed than those containing linseed oil. The ratio of $t-C_{18:1}$ to CLA was lower in the culture solutions containing linseed oil up to 12h incubations as compared to those containing ground linseed.

• The Korean Journal of Mycology
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• v.38 no.2
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• pp.172-178
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• 2010

The contents of proximate composition, free amino acids and phenolic acids in the Fomitella fraxinea cultivated-Rhus verniciflua stem bark(FRVSB), and its adipogenesis effect were investigated. The proximate composition(%) of FRVSB was as follows: moisture(7.64), ash(6.30), crude fat(3.86), crude protein(3.59) and sugar(not detected); while Rhus verniciflua stem bark(RVSB) contained 1.64, 8.09, 7.28, 6.48 and 5.39, respectively. The total free amino acids concentration was 97.41 mg% in FRVSB and 71.91 mg% in RVSB. Phosphoserine(55.06 mg%), ammonia(17.84mg%) and aspartic acid(6.05mg%) were predominant amino acids. The content of total phenolic acids was 422.89 ppm in ethanol extract and 283.86 ppm in water extract, with syringic and gallic acid as the main component. The FRVSB extracts showed a potent free radical scavenging activity for DPPH(2,2-diphenyl-1-picrylhydrazyl hydrate) with $IC_{50}$ of $28.54\;{\mu}g$(EtOH) and $54.70\;{\mu}g$(water), respectively, whereas $IC_{50}$ value of gallic acid was $1.84\;{\mu}g$. The protective effect of both ethanol and water extract the extracts against UV-induced oxidative stress in NIH3T3 was observed. The water extracts of FRVSB may promote adipogenesis in 3T3-L1 cells.

• Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.43-50
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• 2005

We evaluated the nutritional composition of the siphon of the surf clam Tresus keenae in regard to the presence of nitrogenous [amino acids, nucleotides and their related compounds, total creatinine, betaine, trimethylamine oxide (TMAO), and trimethylamine (TMA)] and non­nitrogenous compounds (sugars and organic acids), lipid fatty-acid composition, and occurrence of minerals. The content of total free amino acids was 660.27 $\pm$ 7.94 mg/100 g, and the predominant amino acids were arginine, alanine, sarcosine, glycine, and glutamic acid. These amino acids accounted for $71\;\%$ of the total free amino acids. Among the nucleotides and their related compounds, inosine was the major component and comprised 40.38 $\pm$ 0.02 mg/100 g. Free amino acids were the largest contributor to total extracted nitrogen, comprising $49.94\%$, followed by total creatinine, betaine, nucleotides, and ammonia; the contribution of TMAO and TMA was small. For the non-nitrogenous compounds, malic acid, propionic acid, and succinic acid comprised the major portion of the ten kinds of organic acids detected, and the sugars found were glucose, maltose, and arabinose, which were estimated to be $147.0\pm7.15,\;34.45\pm1.09,\;and\;1.21\pm0.02\;mg/100\;g,$ respectively. The predominant minerals were Na and K, which comprised $11.43\pm1.06\;and\;9.46\pm1.02\;mg/100\;g,$ respectively. The major fatty acids were C22:6, C20:5, C23:0, C18:3, and C16:0 in the lipid fractions. The 23:0 level of glycolipid (GL) was the highest of any other lipid fraction. The amount of total polyunsaturated fatty acids (PUFA) in the lipid fractions was higher, ranging from $58.22\%\;in\;GL\;to\;77.1\%$ in phospholipid (PL), compared to the saturated and monounsaturated fatty acids. Of the n-3 fatty acids, C20:5 and C22:6 contributed $35.30-64.44\%$ of PUFA in the lipid fractions. The ratios of n-3 to n-6 PUFA in total lipid (TL), neutral lipid (NL), PL, and GL were 4.35, 4.26, 6.69, and 2.04, respectively.

• Food Science and Preservation
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• v.10 no.1
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• pp.75-79
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• 2003

Total nitrogen(TN) contents in all samples were in the range of 308.3 to 925.9 mg% and TN value of kanjang prepared with high pressure(HPK)-heated bean was lower than that of normal pressure(NPK) and steam(SPK)-heated bean. TN content was slightly increased according to the heating time of bean. Amino type nitrogen(AIN) contents in all samples were in the range of 133 to 451.5 mg％ and AIN value of NPK(451.5 mg%) was higher than that of HPK(133∼171.5 mg%) and SPK(178.9∼224 mg%). Ammonia type nitrogen(AON) contents in all samples were in the range of 23.5 to 142.0 mg% and AON value of HPK was lower than that of HPK and SPK. Free amino acid(FA) contents in all samples were in the range of 133 to 451.5 mg%, and then FA content of NPK was higher than that of SPK(178.9∼224 mg%) and HPK(133 ∼171.5 mg%). Lightness(L) value of Hunter color in all samples were in the range of 45.13 to 49.08 and was similar with each other. Redness(a) and yellowness(b) value were in the range of 25.30∼34.43 and 52.55∼74.13, respectively.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.587-598
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• 2000

Urea in the oral cavity is hydrolyzed mainly by bacterial ureases to ammonia, which in turn, raises pH of the oral environment, maintaining oral pH homeostasis, thereby inhibiting dental caries. Streptococcus salivarius has been shown to be a major contribution to oral ureolysis. Synthesis of urease by S. salivarius appears to be constitutive, but can be greatly enhanced in the acidic environment. It has been presumed that ureolytic activity of S. salivarius strains isolated from caries-active site is greater than that of strains from caries-free site. However, no in vivo study has supported the presumption. The present study was performed to observe the ureolytic activity of S. salivarius strains isolated from different environments in the same individual, finding out whether the ureolytic activity is related to dental caries. For the purpose, S. salivarius strains were isolated from caries-active site (>C2), a caries-free site of the tooth, and the dorsum of the tongue of each of 50 patients having decayed teeth. The strains isolated from the patients who harbored S. salivarius in more than two sites were selected and then their ureolytic activities were measured. In order to examine clonal diversity of the strains, their ureC genes were amplified by polymerase chain reaction (PCR) and then restricted with EcoRV, and the protein profiles of the strains were compared by SDS-PAGE. The results were as follows: 1. Of 50 patients, 13 patients harbored S. salivarius in more than two sites; a total of 61 S. salivarius strain were isolated from the patients and selected for the study. 2. Of 17 isolates from the caries-active site of 9 patients harboring S. salivarius in more than two sites including carious lesion, 10 (58.8%) showed a high ureolytic activity (> 200 ${\mu}mol/min/mg$). While, 19 out of 44 isolates (43.2%) from the caries-free site of the teeth and the dorsum of the tongues of 13 patients were the strains with a high ureolytic activity. 3. Of 9 patients harboring S. salivarius in more than two sites including caries-active site. 6 patients were found to have the strains in the caries-active site showing a lower ureolytic activity than the strains in the other sites. 4. Of 34 isolates with ureolytic activity higher than 40 ${\mu}mol/min/mg$, 32 isolates produced 0.54-Kbp PCR products regardless of the sites of bacterial collection. In contrast, of 27 isolates with ureolytic activity lower than 40${\mu}mol/min/mg$, 26 isolates yielded 1.3-Kbp PCR products or none regardless of the sites. 5. Different clonal types of S. salivarius with relatively higher and lower ureolytic activities were found in the same individuals and even in the same sites. 6. None of strains showing different ureolytic activity appeared to be the same clonal type. The overall results suggest that ureolytic activity of the isolates does not appear to be related to differences of the environments but related to their own genetic traits.

• Resources Recycling
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• v.31 no.4
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• pp.19-25
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• 2022

In this study, tungsten carbide (WC) powder was prepared using a novel recycling process for hard metal sludge that does not use ammonium paratungstate. Instead of ammonia, acid was used to remove the sodium and crystallized tungstate, resulting in the formation of tungstic acid (H₂WO₄). The WC powder was successfully synthesized by the carbothermal reduction of tungstic acid through H₂O decomposition, reduction of WO₃ to W, and formation of WC. The carbon content and holding time at the carbothermal reduction temperature were optimized to remove free carbon from the WC powder. As a result, most of the free carbon in the WC powder prepared from sludge was removed, and the content of free carbon in the synthesized WC powder was lower than that in commercial WC powder. Moreover, the crystallite size of WC prepared from H₂WO₄ was much smaller than that of commercial micron-sized WC powder produced from APT. The small crystallite size of WC induces grain growth during the sintering of the WC-Co composite; thus, a WC-Co composite with large WC grains was fabricated using the WC powder prepared from H₂WO₄. The large WC grains affected the mechanical properties of the WC-Co composite. Further, due to the large grain size, the WC-Co composite fabricated from H₂WO₄ exhibited a higher toughness than that of the WC-Co composite prepared from commercial WC powder.