• 한국염색가공학회지
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• 제16권1호
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• pp.53-58
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• 2004

The preparation of responsive fibers from acrylic fibers is studied. Various responsive fibers, such as fibers which change their color on exposure to light or with change in temperature, have been developed and are used commercially However, the responsive material in these fibers are not the fiber itself but chemicals in microcapsules attached to the fibers by finishing, and few fibers exhibit responsive properties by itself. The partial hydrolysis of polyacrylonitrile fibers to obtain pH responsive fibers is presented in this paper. Partial hydrolysis was effected by control of the concentration of the sodium hydroxide used in the hydrolysis, hydrolysis temperature and time. The degree of hydrolysis was evaluated by nitrogen content of the hydrolyzed fibers and their response, change in length, to aqueous solutions of varying pH was studied by continually changing the pH. Significant changes in lengths with pH were observed and the gel transition behavior varied with the conditions of hydrolysis. The hysteresis of the length change was also studied to evaluate the possibilities of using hydrolyzed acrylic fibers as pH sensors.

• Archives of Pharmacal Research
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• 제18권6호
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• pp.454-457
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• 1995

To improve the yield of genuine aglycones from glycosides, the conditions of alkaline hydrolysis were investigated, and a modified method was established. The modified method empolyed pyridine as an aprotic solvent. To complete the hydrolysis and obtain 20(S)-protopanaxadiol (1) and 20(S)-protopanaxatriol(2), which are the genuine aglycones of ginsenosides, total ginsenosides were refluxed with sodium methoxide in pyridine. Addition of methanol, a protic polar solvent to the reaction miuxture, led partial hydrolysis yielding a mixture of the genuine prosapogenols. Of the prosapogenols compound 3 and 6 characteristically possessed D-glucopyranosyl moiety attached at the sterically hindered C-20 hydroxyl group. 3 and 6 were not obtaijned by other hydrolysisw methods except by the soil bacterial hydrolysis.

• 공업화학
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• 제25권2호
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• pp.152-156
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• 2014

Isoquercitrin (IQ)은 폴리페놀의 일종인 quercetin (QU)의 3번 위치에 glucose가 하나 결합해 있는 배당체로서, 천연에는 미량만이 존재하고 있다. 최근 QU의 2배당체인 rutin (RU)을 기질로 사용하여 효소에 의한 부분 가수분해에 의해 IQ를 합성할 수 있다는 것이 알려졌다. 본 논문에서는, $Pecinex^{TM}$ 계열의 복합 효소를 사용하여 RU의 선택적 가수분해에 의해 IQ를 합성하는 반응에서 최적 효소를 선정하고, 효소량 및 반응물의 농도 등의 변수에 따른 반응성을 검토하였다. 그 결과, $50^{\circ}C$에서 1%의 반응물 농도로 RU 1 g 대비 8 mL의 Ultra Clear를 사용하는 것이 반응 속도 및 IQ의 선택성 측면에서 최적인 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제18권3호
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• pp.300-305
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• 1997

Effect of a nonionic surfactant, Tween 20 on the adsorption and kinetic mechanism for the hydrolysis of a microcrystalline cellulose, Avicel PH 101, by endoglucanase Ⅰ (Endo Ⅰ) and exoglucanase Ⅱ (Exo Ⅱ) isolated from Trichoderma viride were studied. The Langmuir isotherm parameters, amount of maximum adsorption (Amax) and adsorption equilibrium constant (Kad) for the adsorption, were obtained in the presence and the absence of nonionic surfactant. On the addition of Tween 20, the Kad and Amax values of Exo Ⅱ were decreased, while those of Endo Ⅰ were not affected. These indicate that the adsorption affinity of Exo Ⅱ on the cellulose is weakened by nonionic surfactant, and the surfactant enhanced desorption of Exo Ⅱ from insoluble substrate. The enzymatic hydrolysis of the cellulose can be described by two parallel pseudo-first order reactions using the percentages of easily (Ca) and hardly (Cb) hydrolyzable cellulose in Avicel PH 101 and associated rate constants (ka and kb). The Ca value was increased by adding Tween 20 for all enzyme samples (Exo Ⅱ, Endo Ⅰ and their 1:1 mixture) implying that the low-ordered crystalline fraction in the cellulose may be partly dispersed by surfactant. The ka value was not affect by adding Tween 20 for all enzyme samples (Exo Ⅱ, Endo Ⅰ and their 1:1 mixture). The kb value of Exo Ⅱ was increased by adding Tween 20, while that of Endo Ⅰ was not affected. This suggests that the surfactant helps the Exo Ⅱ desorb from microcrystalline cellulose, and increase the hydrolysis rate. These results were show that the increase of hydrolysis of cellulose by the nonionic surfactant is due to both the activation of Exo Ⅱ and partial defibrillation of the cellulose.

• 한국식품과학회지
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• 제16권2호
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• pp.228-234
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• 1984

탈지 대두박으로 부터 추출 분리하여 얻어진 분리대두 단백질에 효소(pepsin 및 trypsin)를 처리하여 부분적 단백질 가수분해물을 만들고 이들 제품의 가수분해 정도를 고유점도 측정, 수용성 단백질 및 유리아미노산 농도 측정과 전기영동등으로 평가하였으며 가수분해물의 유체변형성과 식품기능성외 변화를 평가하였다. 가수분해물의 고유점도는 사용된 효소의 종류와 처리시간에 따라 변화하였으며 가수분해에 의한 수용성 단백질의 농도 변화와 일반적으로 역비례 하였다. 0.03 M$CaCl_2$, 용액에서의 용해도와 ninhydrin test에 의한 TCA가용성 단백질 함량은 고유점도의 변화와 밀접한 상관관계를 나타내었으므로 가수분해 정토를 나타내는 지표로 사용될 수 있었다. S. D. S. - P. A. G. 전기영동 패턴은 사용한 효소와 처리시간에 따라 다른 형태를 나타냈으며 pepsin처리에 있어서는 가수분해 정도가 증가함에 따라 주로 11S분획이 선택적으로 분해되었으며 trypsin처리에 있어서는 7S와 11S모두 영향을 받았다. 가수분해물의 흐름형태는 4%용액에서 거의 New tonian 유체형태를 나타내었으며 apparent viscosity는 가수분해 정도가 증가함에 따라 감소하였다. 유화용량 및 유화안정도는 SPI보다 모두 낮은 값을 나타냈으며 같은 효소처리인 경우 가수분해 정도가 증가함에 따라 감소하는 경향을 나타내었다. 기포형성은 SPI보다 현저하게 증가하였으나 기포안정도는 가수분해 정도가 증가함에 따라 급격하게 감소하는 경향을 나타내었다.

• KSBB Journal
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• 제14권2호
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• pp.220-224
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• 1999

본 논문에서 회분식 반응 증류에 의한 lactic acid의 분리 특성을 연구하였다. 휘발성이 있는 lactate ester의 생성을 위한 lactic acid와 alcholo과의 반응에서, 반응에 의해 생성된 lactate ester의 휘발성이 높을 수록 증류탑으로 들어가는 lactate ester양은 증가하여 재비기에서 얻어진 lactic acid의 회수율은 증가 하였다. 부분응축기의 온도가 감소할수록 재비기로 모이는 lactate ester양은 증가하였고 재비기 내의 수화 반응에 의해 얻어지는 lactic acid의 양은 증가하였다 Lactic acid의 정제를 위한 lactate ester와 물과의 수화 반응은, 비록 증류탑 내에서 lactate ester와 물이 반응을 할 수 있으나, 증류탑 내에서의 체류시간이 짧기 때문에 대부분 재비기에서 이루어진다.

• 한국잠사곤충학회지
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• 제39권2호
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• pp.186-196
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• 1997

The IR crystallinity index of Calcium nitrate treated silk fiber decreased proportionally to the concentration of calcium nitrate. A partial change of conformation was observed in the concentration of over 46.4-47.6% changing from $\beta$-sheet or to random coil in the crystalline region. This is in coincidence with the result of crystallinity index, which was started to be reduced in the concentration range of 46.4-47.6%. A same trend was observed for the X-ray order factor, birefringence, degree of orientation and surface structure. These structural parameters were remarkably changed on the treatment of silk fibers with concentration of 46.4-17, 6% calcium nitrate. Therefore, it seems that there exists a critical concentration of calcium nitrate in affection the structure and morphology of silk fibers. According to the examination of surface morphology, the fine stripe was observed in the direction of fiber axis at 46.4% concentration. However, the treated concentration was exceeded by 47.6%, the cracks were appeared severely on the fiber surface in the transverse direction as well as fiber axis direction. This result might be related to the tensile properties, specially a tenacity of silk fibers. As a result of quantitative analysis of a dilute acid hydrolysis, three different regions, which are known as a amorphous, semi-crystalline and crystalline region, could be obtained. The hydrolysis rate curves were different with various concentrations of treatment and the relative contents of each region could be calculated.

• Preventive Nutrition and Food Science
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• 제11권2호
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• pp.146-154
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• 2006

Structural modification of corn starch by gamma irradiation was evaluated for under dry conditions at varied intensities from 0 to 40 kGy. Under scanning electron microscopy, the granule shape of corn starch was not significantly affected by the irradiation up to 40 kGy. In addition, X-ray diffraction and melting patterns of the irradiated starches were similar to those of the native starch, indicating that crystalline regions in the starch granules were not changed by irradiation. However, the pattern of gel permeation column chromatography showed a significant increase in partial hydrolysis of gamma irradiated starch samples. The degree of polymerization and the paste viscosity of irradiated starch samples dose-dependently decreased significantly with irradiation, and increased solubility and clarity were observed in the irradiated starch solution. In addition, the degree of retrogradation decreased as irradiation dose increased. Irradiation of corn starch has advantages over the ordinary acid or the enzyme hydrolysis modification methods. It does not affect the granular shape and crystalline phase of starch during hydrolysis, and the process can be carried out in dry state.

• 한국세라믹학회지
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• 제32권7호
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• pp.783-792
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• 1995

Sol-Gel derived ferroelectric PZT thin films were fabricated on ITO/Glass and Si/SiO2 substrates. In order to investigate the effect of catalysts on the densification and crystallization of PZT thin films, a nitric acid or ammonium hydroxide was added to the PZT stock solution at the state of partial hydrolysis reaction. The measured pH for a stable PZT sol was 5.2~9.3. In case of an acid-catalyzed PZT sol, a highly condensed particulate PZT sol was formed by accelerating the hydrolysis reaction. But weakly branched polymeric PZT sol was formed with a base-catalyzed condition. The difference in densification behavior was not found in the pH range of added catalyst, but the refractive index of PZT thin film was increased rapidly as the annealing temperature increased. The PZT thin film annealed at 54$0^{\circ}C$ for 10 min was fully densified and its refractive index was above 2.4. When the annealing temperature increased, the transition from the pyrochlore phase to perovskite appeared at 54$0^{\circ}C$. The base-catalyzed PZT thin film suppressed to form the pyrochlore phase and proceeded effectively to convert the perovskite phase. This was due to the formation of polymeric molecular structure by controlling the hydrolysis and condensation reaction through the additiion of the ammonium hydroxide.

• 한국표면공학회지
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• 제23권2호
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• pp.18-23
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• 1990

Thin films of tin oxide were prepared by chemical vapor deposition (C.V>D) using the hydrolysis reaction of SnCl4, Deposition rate increased with the increase of temperature up to $500^{\circ}C$and then decreased at $700^{\circ}C$, Deposition rate with SnCl4 partial pressure showed RidealEley behavir. It was found that SnO2 thin film deposited at the temperature above $400^{\circ}C$ had(110) and (301) plane preferred orientation with crystallinity of rutite structure. Electrical resisvity of SnO2 thin film decreased with increase increase of deposition temperature and showed minimum value of 10-3 ohm at $500^{\circ}C$and than largely increased increased with further increase of deposition temperture.