• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.301-304
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• 1988

A pH-meter has been newly developed by using on ISFET as the ion sensing element. The performance characteristics of the developed pH-meter have been investigated and confirmed to be used practically. The stable operation and the temperature compensation were stressed in this study.

• Archives of Pharmacal Research
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• v.20 no.6
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• pp.643-646
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• 1997

Thermal stability of a red pigment, carthamin, frm Carthamus tinctorius was investigated to explore possible applications as natural color additives for foods, cosmetics, and nutraceuticals. Degree of degradation reactions of carthamin at acidic, neutral and alkaline conditions were determined with UV/V is spectral measurements. Decomposition half lives of carthamin at 25.deg. C were 4.0 h, 5.1 h, and 12.5 h at pH 5.0, pH 7.0, and pH 12.0, respectively, indicating that carthamin is much more stable at alkaline pH than acidic or neutral conditions. The activation energies of carthamin at pH 5.0, pH 7.0, and pH 12.0 were 15.6, 15.7 and 16.8 kcal/mol, respectively.

• Applied Biological Chemistry
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• v.12
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• pp.7-11
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• 1969

Mucor-rennin, the crystalline milk-clotting enzyme, isolated from Mucor pusillus var. Lindt, has an acid protease activity. The optimum pH for the digestion of k-casein is 4.5, while that for hemoglobin digestion is 4.0. The skim milk solution was easily clotted acidic solution than alkalin solution, and the milk clotting activated by Ca ion. The enzyme was heat stable against heat from pH 4.0 to 6.0 but was more stable at pH 5.0. The activity of the enzyme at pH 5.0 did not decrease at 30 C for 15 days and the activity was not effected by sodium propionate and salicilic acid. Therefore, the enzyme of liguid type could store for a long time and could be transported from Erzyme production Co. to Manufacture of cheese Co. by adding the antiesptic and by adjusting pH to 5.0.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.6
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• pp.52-54
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• 1982

p·Si-전해질 접합을 전해질로 6N H2SO4, 6N H2SO4(Ti3+), 6N H2SO4(Ti4+), 6N H2SO4(Ti4+/Ti3+)을 사용하여 만들었다. 이들 전해질중 6N H2SO4(Ti4-/Ti3+)을 사용할 때 p·Si 광음극이 안정하게 동학하며 높은 광전 감도를 가지고 있었다. p·Si-electrolyte junction are prepared by using p·Si photocatode in four different electrolytes such as 6N H2SO4, 6N H2SO4(Ti3+), 6N H2SO4(Ti4+), 6N H2SO4(Ti4+/Ti3+) respectively. Among those electrolytes 6N H2SO4(Ti4-/Ti3+) shows very good results, in which p·Si photocathode is stable.

• Korean journal of food and cookery science
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• v.12 no.4
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• pp.506-510
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• 1996

The stability of prickly pear color as affected by pH, metal ions, sugar and acids was studied. The color of prickly pear was most stable at pH 4 and 5. Metal ions (Fe, Cu) at a level of 100 ppm caused a decrease in stability compared to that of the control, whereas pigment of prickly pear was stable at 100 ppm of Sn ion And the color of prickly pear was stable at 0.15 M fructose. Both 100 and 500 ppm ascorbic acid had the greatest effect on stability, while citric acid, phosphoric acid and tartaric acid had no effect on stability compared to that of the control. Based on the data presented, it was concluded that under selected conditions prickly pear pigment should find application as natural food colorants.

• Journal of Microbiology and Biotechnology
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• v.23 no.5
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• pp.661-667
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• 2013

Lipase-producing bacterial strains were isolated from Antarctic soil samples using the tricaprylin agar plate method. Seven strains with relatively strong lipase activities were selected. All of them turned out to be Bacillus pumilus strains by the 16S rRNA gene sequence analysis. Their corresponding lipase genes were cloned, sequenced, and compared. Finally, three different Bacillus pumilus lipases (BPL1, BPL2, and BPL3) were chosen. Their amino acid sequence identities were in the range of 92-98% with the previous Bacillus pumilus lipases. Their optimum temperatures and pHs were measured to be $40^{\circ}C$ and pH 9. Lipase BPL1 and lipase BPL2 were stable up to $30^{\circ}C$, whereas lipase BPL3 was stable up to $20^{\circ}C$. Lipase BPL2 was stable within a pH range of 6-10, whereas lipase BPL1 and lipase BPL3 were stable within a pH range of 5-11, showing strong alkaline tolerance. All these lipases exhibited high hydrolytic activity toward p-nitrophenyl caprylate ($C_8$). In addition, lipase BPL1 showed high hydrolytic activity toward tributyrin, whereas lipase BPL2 and lipase BPL3 hydrolyzed tricaprylin and castor oil preferentially. These results demonstrated that the three Antarctic Bacillus lipases were alkaliphilic and had a substrate preference toward short- and medium-chain triglycerides. These Antarctic Bacillus lipases might be used in detergent and food industries.

• Journal of the Korean Electrochemical Society
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• v.11 no.4
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• pp.304-308
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• 2008

Noble Poly (lithium 2-acrylamido-2-methyl propane sulfonate) and its copolymer with N-vinyl formamide based on trihexyl (tetradecyl) phosphonium acetate [$(C_6H_{13})_3$ P ($C_{14}H_{29}$) $CH_3COO$; $P_{66614}$ $CH_3COO$] and trihexyl (tetradecyl)phosphonium bis(trifluoromethane sulfonyl) amide ([$(C_6H_{13})_3P(C_{14}H_{29})$] [TFSA];$P_{66614}TFSA$) were prepared and analyzed to determine their characteristics and properties. The ionic conductivity of a copolymer based $P_{66614}TFSA$ ionic liquid system exhibits a higher conductivity ($8.9{\times}10^{-5}Scm^{-1}$) than that of a copolymer based $P_{66614}CH_3COO$ system ($1.57{\times}10^{-5}Scm^{-1})$. The charge on the TFSA anion is spread very diffusely through the S-N-S core and particularly in the trifluoromethane groups, and this diffusion results in a decreased interaction between the cation and the anion. The viscosity of $P_{66614}TFSA$ (39 cP at 343 K) and $P_{66614}CH_3COO$ (124 cP at 343 K), which is very hydrophobic, was fairly high. High viscosity leads to a slow rate of diffusion of redox species. The ionic conductivity of copolymer of a phosphonium ionic liquid system also exhibits higher conductivity than that of a homopolymer system. Phosphonium ionic liquids were thermally stable at temperatures up to $400^{\circ}C$.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.177-182
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• 2006

Polyphenol oxidase (PPO) was isolated from the flesh of Fuji apples by DEAE-Cellulose, ammonium sulfate precipitation, phenyl-Sepharose CL-4B, and Sephdex G-100 chromatography. The molecular mass of the purified PPO was estimated to be 40 kDa by SDS polyacrylamide gel electrophoresis. With regard to substrate specificity, maximum activity was achieved with chlorogenic acid as substrate, followed by catechin and catechol whereas, there was no detectable activity with hydroquinic acid, resorcinol, or tyrosine as substrate. The optimum pH and temperature with catechol as substrate were 6.5 and $35^{\circ}C$, respectively. The enzyme was most stable at pH 6.0 and unstable at acidic pH. The enzyme was stable when it was heated to $45^{\circ}C$ but heating at $50^{\circ}C$ for more than 30 min caused 50% loss of activity. Reduced $ZnSO_4$, L-cystein, epigallocatechin-3-o-gallate (EGCG), and gallocatechin gallate (GCG) also inhibited activity.

• Applied Biological Chemistry
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• v.13 no.3
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• pp.231-235
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• 1970

1. Purification of amylase system produced from Humicola sp. by a submerged culture eras carried out. 2. By DEAE-Cellulose column chromatography amylase system was separated into two fractions eluted at 0.05M and 0.5M phosphate buffer solution of pH 6.0. 3. The saccharogenic amylase was mostly composed of. the fraction of 0.05M phosphate buffer solution of pH 6.0 while the dextrinogenic amylase was perseted in fraction of 0.5M phosphate buffer solution of pH 6.0 4. It was found that the optimum pH of this saccharogenic amylase was within the range of from 4.5 to 5.5, stable pH was within the range of from 4.0 to 9.0 and optimum temperature was $60-65^{\circ}C$. This amylase was stable at $70^{\circ}C$ for ten minutes but completely inactivated $80^{\circ}C$ above.

• Applied Biological Chemistry
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• v.21 no.2
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• pp.103-108
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• 1978

Acid-stable ${\alpha}-amylase$ was partially purified from Paecilomyces subglobosum by Sephadex G-150 gel filtration. About 7.7-fold purification was obtained and the partially purified preparation has 5.0 U of ${\alpha}-amylase$ activity per mg of protein. Using this partially purified ${\alpha}-amylase$, general properties were studied and it showed the maximal activities at the conditions of pH 4.0 and $38^{\circ}C$. High stability of the acid-stable ${\alpha}-amylase$ in acidic condition was observed, whereas thermal stability was similar to the conventional ${\alpha}-amylase$.