• Bulletin of the Korean Chemical Society
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• 제26권7호
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• pp.1109-1111
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• 2005

• Journal of Microbiology and Biotechnology
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• 제17권1호
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• pp.116-122
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• 2007

An efficient enzyme system for the synthesis of L-tyrosine was developed using a fed-batch reactor with continuous feeding of phenol, pyruvate, and ammonia. A thermo- and chemostable tyrosine phenol-lyase from Symbiobacterium toebii was employed as the biocatalyst in this work. The enzyme was produced using a constitutive expression system in Escherichia coli BL21, and prepared as a soluble extract by rapid clarification, involving treatment with 40% methanol in the presence of excess ammonium chloride. The stability of the enzyme was maintained for at least 18 h under the synthesis conditions, including 75 mM phenol at pH 8.5 and $40^{\circ}C$. The fed-batch system (working volume, 0.51) containing 1.0 kU of the enzyme preparation was continuously fed with two substrate preparations: one containing 2.2 M phenol and 2.4 M sodium pyruvate, and the other containing 0.4 mM pyridoxal-5-phosphate and 4M ammonium chloride (pH 8.5). The system produced 130g/I of L-tyrosine within 30h, mostly as precipitated particles, upon continuous feeding of the substrates for 22 h. The maximum conversion yield of L-tyrosine was 94% on the basis of the supplied phenol.

• Applied Biological Chemistry
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• 제33권1호
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• pp.87-92
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• 1990

Ergosterol을 생산하기 위하여 Saccharomyces sake KBA No. 6가 사용되었으며 ergosterol축적에 관여하는 각종 요인들이 검토되었다. 가장 효율적인 무기 질소원은 ammonium chloride이었으며, C/N 비율이 200/l이었을 경우 3.5%의 ergosterol이 세포 내에 축적되었다. Tween 80 0.2 %와 potassium nitrite 0.1 %를 동시에 사용하였을 경우, ergosterol 함량(%) 과 총 ergosterol량(mg/L)은 각각 56 %와 45% 증가하였다. 최적조건에서 ergosterol 함량은 1.73%에서 5.3%로 증가하였으며, 총 ergosterol량은 65.2 mg/L에서 135.15 mg/L로 증가하였다.

• 한국응용과학기술학회지
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• 제19권4호
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• pp.339-348
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• 2002

Self-diffusion coefficients of colloidal ass9Ciation structures in the aqueous solutions of anionic ammonium dodecyl sulfate (ADS) and cationic octadecyltrimethylammonium chloride (OTAC) surfactants were measured by pulsed-gradient spin echo NMR. The results were interpreted on the basis of the ADS/OTAC/water phase diagram. Crossing the phase boundaries, significant changes in self diffusion coefficients were observed and well correlated to the phase diagram. For the micelles their apparent radii were obtained from Stokes-Einstein equation. Their values were 15 for the ADS micelles and 54 ${{\AA}}$ for the OTAC micelles, respectively. For vesicles which were formed spontaneously at different relative amounts of the surfactants and total surfactant concentrations, the radius was measured as 50 to 200 nm. This result is in fair agreement with those by TEM and light scattering.

• 펄프종이기술
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• 제36권1호
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• pp.1-8
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• 2004

One of the most frequently used method for measurement of the degree of sizing (viz., hydrophobicity) is the Stockigt test. However, the Stockigt test was influenced by various factors such as dropping height, dropping amount, dropping speed and viewing angle. The resultant data of the sizing degree on the same specimen also varied according to different testers. Thus, the Stockigt test should be modified to be regarded as a highly reliable and reproducible standard method. For modifying the Stockigt test, it was required to quantify red coloration by reaction between 1％ ferric chloride and 2％ ammonium thiocyante during Stockigt testing. The cameras capturing the serial images during the red coloration process were the CMOS (Complementary Metal Oxide Semiconductor)-type and CCD (Charge Coupled Device)-type cameras. For measurement based on KS M 7025, the CCD-type camera must be used due to its high resolution, and on the other hand, for measurement based on Tappi Useful Method 429, the CMOS-type camera may be used owing to its low resolution. It was needed to covert the RGB values of a droplet image into HSV(Hue, Saturation, and Value) values because the human eyes are much closer to HSV than RGB. Among HSV values, the Hue value was accepted as the most reliable index consistent with the red coloration process by excluding the surrounding conditions such as light, tester's movement etc.

• 한국환경보건학회지
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• 제16권2호
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• pp.11-20
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• 1990

To investigate ionic characteristics of acid rain by the succeeding rainfall. bulk precipitation was collected every each 5mm rainfall from march to october 1990 at Dae Jeon area. pH, sulfate nitrate, chloride, ammonium ion was measured and analyzed. The result was as follows: 1. The weighted average pH of rain was 5.1$\pm$ 0.72(4.15~7.6) and rain pH less than 5.5 was appeared 51.3% 2. Average ion concentrations of sulfate, nitrate, chloride and ammonium ion was 125.12 $\mu$eq/l, 62.38 $\mu$eq/l, 31.95 $\mu$eq/l, 66.6 $\mu$eq/l and rates of each anions was 57%, 28.4%, 14.6% and rate of sulfate by nitrate was 2 times. 3. There is no correlations time interval of rainfall and Ion concentration change. 4. From initial to 15mm rainfall, each ion concentrations were decreased. and average concentration of pH, SO$^{-2}_{4}$, Cl ion concentration was increased in the succeeding rainfall 5. Only sulfate ion was correlated by the simple regression analysis with pH except NO$^{-}_{3}$, Cl$^{-}$ and NH$_{4}^{+}$ Cl$^{-}$ correlation coefficient was very high at the multiple regression analysis with pH. 6. Simple & multiple correlation coefficient among anions and NH$^{+}_{4}$ was very high especially N$^{+}_{4}$ and SO$^{2-}_{4}$ at simple regression analysis and SO$^{-2}_{4}$ and NO$_{3}^{-}$, Cl$^{-}$, NH$_{4}^{-}$ at multiple regression analysis.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.335-339
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• 2005

정어리에서 분리한 균주 중 가장 항산화력이 강한 균주를 5개를 선발하여 이를 antiangiogenesis test를 통하여 효과가 가장 뛰어난 균주인 ${\lambda}-28$번 균주를 선발하였다. 균주의 최적 배지를 제조하기 각기 다른 온도, 영양성분등을 투여하여 최적의 조건을 알아보았다. 온도에 있어서는 균주의 특성상 바다온도와 가장 비슷한 $25^{\circ}C$에서 가장 좋은 성장률을 보였고 영양적인 측면에서 보면 탄소원에서는 glucose가 균주 성장률이나 항산화력에서 다른 첨가물에 비해 유효한 효과를 보였고, 무기 탄소원에서 ammonium chloride가 좋은 항산화력을 보였다. 유기 탄소원을 첨가한 실험에서는 유효한 효과가 나타나지 않았다.

• 생약학회지
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• 제33권1호통권128호
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• pp.13-17
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• 2002

Helicobacter pylori infection is associated with type B gastritis, peptic ulcer, and gastric cancer. The vacuolation of cells induced by H. pylori is thought to be essential for the initiation and maintenance of gastric infection. The roles of H. pylori cytotoxin, urease, and ammonia in the vacuolation of HeLa cells were determined. Ammonium chloride augmented the neutral red uptake induced by H. pylori toxin. Acetohydroxamic acid (AHA) failed to block the neutral red uptake induced by H. pylori toxin. Leweifang significantly prevented the vacuolation of HeLa cells induced by H. pylori toxin or H. pylori toxin and ammonium chloride. Further investigation is required to determine the mechanisms of Leweifang for the inhibition of vacuole formation of eukaryotic cells in response to the H. pylori toxin.

• Korean Chemical Engineering Research
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• 제50권1호
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• pp.61-65
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• 2012

이성분 용융액의 시간의존형 응고계에서 mush 층의 대류발생을 선형 안정성 이론으로 해석하였다. 본 연구에서는 근공융물 mush 층을 다공성 블록으로 가정한 단순화된 모델에 전파이론을 적용하여 대류발생 임계조건을 구하였다. 본 연구 모델에서는 기존의 실험결과 및 mush층 위의 액체층을 포함하여 고려한 이론적 연구의 결과보다 더 높은 임계 Rayleigh 수가 얻어졌다. mush 층의 윗 경계면에 일정압력(투과)조건을 적용하는 경우가 비투과조건에 비해 임계 Rayleigh 수를 더 작게 하며 염화암모늄 수용액의 응고실험결과와 더 근접한 것으로 조사되었다.

• 폴리머
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• 제25권2호
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• pp.263-269
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• 2001

나트륨 몬모릴로나이트($Na^{+}$-MMT)의 양이온을 3-(methacryloyl amino) propyl trimethyl ammonium chloride (MAPTAC)와 교환반응시켜 몬모릴로나이트의 표면을 친유성으로 개질시키는 동시에, 단량체와 공중합을 할 수 있는 이중결합이 부착된 MAPTAC-MMT를 제조하였다. 상온에서 MAPTAC-MMT가 분산된 수용액에서 N-isopropyl acryl amide (NIPAM)를 중합하여 열응답성 나노복합재료(PNIPAM-MMT)를 제조하였다. MAPTAC-MMT으로부터 제조된 열응답성 나노복합재료는 열응답성 고분자인 poly(N-isopropyl acrylamide) (PNIPAM)와 마찬가지 하한임계용액온도(LCST)를 나타내었으며, MAPTAC-MMT의 양이 증가함에 따라 PNIPAM-MMT의 LCST는 감소하였다. 또한 TGA실험 결과에서 열응답성 나노복합재료의 열안정성이 열응답성 고분자에 비하여 우수하였음을 보였다.