• Journal of the Korean Wood Science and Technology
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• 제43권5호
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• pp.672-681
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• 2015

As a part of abating the formaldehyde emission of amino resin-bonded wood-based composite panels, this study was conducted to investigate hydrolytic stability of urea-melamine-formaldehyde (UMF) resin depending on various hydrolysis conditions and hardener types. Commercial UMF resin was cured and ground into a powdered form, and then hydrolyzed with hydrochloric acid. After the acid hydrolysis, the concentration of liberated formaldehyde in the hydrolyzed solution and mass loss of the cured UMF resins were determined to compare their hydrolytic stability. The hydrolysis of cured UMF resin increased with an increase in the acid concentration, time, and temperature and with a decrease in the smaller particle size. An optimum hydrolysis condition for the cured UMF resins was determined as $50^{\circ}C$, 90 minutes, 1.0 M hydrochloric acid and $250{\mu}m$ particle size. Hydrolysis of the UMF resin cured with different hardener types showed different degrees of the hydrolytic stability of cured UMF resins with a descending order of aluminum sulfate, ammonium chloride, and ammonium sulfate. The hydrolytic stability also decreased as the addition level of ammonium chloride increased. These results indicated that hardener types and level also had an impact on the hydrolytic stability of cured UMF resins.

• Journal of Microbiology and Biotechnology
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• 제8권6호
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• pp.692-695
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• 1998

Pseudomonas sp. DJ-12 was able to degrade 4-chlorobenzoate by hydrolytic dechlorination to produce 4-hydroxybenzoate and chloride ion. The fcbABC genes responsible for the hydrolytic dechlorination were cloned from the chromosomal DNA of the organism. The genes were found to be organized in the order fcbB-fcbA-fcbC, but there was an intergenic space between the fcbA and fcbC genes.

• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.199-204
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• 2001

A Cryptate (221) having a short alcohol pendant (2) was metallated with europium(Ⅲ) in anhydrous condition, and its hydrolytic activity for phosphate esters at neutral pH was examined. While the activity for the phosphate diester and monoester is comparable to that of the parent metal complex [1Eu]3+, its hydrolytic activity towards a phosphate triester is significantly suppressed. Potentiometric titration and luminescence spectroscopic studies for the equilibrium behavior of the complex in solution suggest that a dimer formation through the metal hydroxides as well as the pendant alcohol is likely to happen. The low hydrolytic activity for the triester seems to be associated with the dimer formation.

• 한국미생물·생명공학회지
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• 제48권1호
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• pp.64-71
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• 2020

A total of 262 bacterial strains were isolated from clay minerals, bentonite and zeolite, in Gyeongsangbukdo, Republic of Korea, and their hydrolytic enzyme activities were analyzed. Most of the isolated strains belonged to Micrococcales and Bacillales order. Of strains, 96 strains produced α-amylase activity, 42 strains showed cellulase activity, 111 strains had pectinase activity, and 70 strains showed protease activity. Among them, 177 isolates exhibited one or more of the hydrolytic enzyme activities and in particular Bacillus cereus MBLB1321, B. albus MBLB1326 and KIGAM017, B. mobilis MBLB1328, MBLB1329 and MBLB1330 showed all of the enzyme activities. These results demonstrate the diversity of functional Bacillus species in clay minerals as vital sources for the discovery of industrially valuable hydrolytic enzymes, which have a great commercial prospect in various bio-industrial applications.

• Macromolecular Research
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• 제12권6호
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• pp.545-552
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• 2004

The long-term stability of sulfonic acid-containing polyimides has been investigated. The hydrolytic degradation of homopolyimide and the block copolyimide comprising $27\;mol\%$ of 2,2'-bis(trifluoromethyl)benzidine and $9\;mol\%$ of m-phenylenediamine (BTFMB27mPl0[7/(3+1)]), was quantified through viscosity measurements and FT-IR spectroscopic analyses. The viscosity decrease with respect to time and the degradation rate were similar. The degrees of degradation with respect to time under ambient conditions and at elevated temperature in water were monitored by FT-IR spectroscopy. A new absorption peak was observed at $1786\;cm^{-1},$ which we corresponds to the presence of anhydride end groups formed by hydrolytic scission of the imide rings.

• 한국환경과학회지
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• 제26권1호
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• pp.1-10
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• 2017

In this study, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/graphene oxide (GO) nanocomposite films containing various content of GO were prepared using solution casting method. The effect of GO content on Young's modulus and dispersion of GO in PHBV matrix was investigated. Also, the thermomechanical properties, oxygen transmission rates and hydrolytic degradation of PHBV/GO nanocomposite films were studied. The addition of GO into PHBV improves the Young's modulus and decreases thermal expansion coefficient. The improvement can be mainly attributed to good dispersion of GO and interfacial interactions between PHBV and GO. Furthermore, PHBV/GO nanocomposite films show good oxygen barrier properties. PHBV/GO nanocomposites show lower hydrolytic degradation rates with increasing content of GO.

• Journal of Preventive Medicine and Public Health
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• 제26권1호
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• pp.74-85
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• 1993

유기용제 취급 근로자들의 간기능 장해의 새로운 지표로서 혈청 Succinyl trialanine p-nitroanilide (STN) 가수분해 효소 활성치에 관한 연구가 신발제조업 제화부서에 근무하는 종사자 114명을 대상으로 시행하여 다음과 같은 결과를 얻었다. 1. 전체 대상자의 간기능 검사치인 혈청 GOT, GPT, ${\gamma}GT$의 평균은 $22{\pm}12.32IU/l,\;20{\pm}9.65IU/l,\;28{\pm}21.35IU/l$였고, 혈청 STN 가수분해 효소 활성치는 $0.08{\pm}0.05$였다. 2. 혈청 STN 가수분해 효소 활성치는 남자에서 통계학적으로 유의하게 높았고(P<0.05), 연령군별로는 차이가 없었다. 3. 일일근무시간별 혈청 STN 가수분해 효소 활성치는 차이는 없었으나, 3년이상 근무한 근로자와 100ppm이상의 톨루엔에 노출된 근로자에서는 혈청 STN 가수분해 효소 활성치가 통계학적으로 유의하게 증가하였다(p<0.05). 4. 톨루엔 노출농도와 혈청 GOT, GPT, ${\gamma}GT$ 및 혈청 STN 가수분해 효소 활성치 사이에는 통계학적으로 유의한 상관관계를 나타냈다(p<0.01). 5. 혈청 STN 가수분해 효소 활성치에 영향을 미치는 요소중에서 톨루엔 노출농도가 가장 설명력이 높고, 통계학적으로 유의하였다(P<0.05).

• Journal of Microbiology and Biotechnology
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• 제13권1호
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• pp.57-63
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• 2003

Using fungal (Fusarium solani f. pisi) and bacterial (Pseudomonas mendocina) cutinases, the initial hydrolysis rate of p-nitrophenyl esters was systematically estimated for a wide range of enzyme and substrate concentrations using a 96-well microplate reader. Both cutinases exhibited a high substrate specificity; i.e. a high hydrolytic activity on p-nitrophenyl butyrate (PNB), yet extremely low activity on p-nitrophenyl palmitate (PNP). When compared to the hydrolysis of PNB and PNP by other hydrolases [lipases and esterases derived from different microbial sources, such as bacteria (Pseudomonas cepacia, Psedomonas furescens, Baciilus stearothermophilus), molds (Aspeillus niger, mucor miehei), and yeasts (Candida rugosa, Candida cylindracea)], the above substrate specificity would seem to be a unique characteristic of cutinases. Secondly, the hydrolytic activity of the cutinases on PNB appeared much faster than that of the other hydrolytic enzymes mentioned above. Furthermore, the current study proved that even when the cutinases were mixed with large amounts of other hydrolases (lipases or esterases), the Initial hydrolysis rate of PNB was determined only by the cutinase concentration for each PNB concentration. This property of cutinase activity would seem to result from a higher accessibility to the substrate PNB, compared with the other hydrolytic enzymes. Accordingly, these distinct properties of cutinases may be very useful in the rapid and easy isolation of various natural cutinases with different microbial sources, each of which may provide a novel industrial application with a specific enzymatic function.

• Journal of the Korean Wood Science and Technology
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• 제39권2호
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• pp.179-186
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• 2011

In an effort to understand the hydrolytic degradation process of cured urea-formaldehyde (UF) resins responsible for the formaldehyde emission of wood-based composite panels, this study analyzed the influence of acid hydrolysis on the morphology of cured UF resins with different formaldehyde/urea (F/U) mole ratios such as 1.6, 1.4, 1.2 and 1.0. Field emission-scanning electron microscopy (FE-SEM) was employed to observe both exterior and fracture surfaces on thin films of cured UF resins before and after the etching with hydrochloric acid as a simulation of the hydrolytic degradation process. FE-SEM images showed that the exterior surface of cured UF resin with the F/U mole ratio of 1.0 had spherical structures after the acid hydrolysis while the other cured UF resins were not the case. However, the fracture surface observation showed that all the samples possessed spherical structures in the cured state of UF resins although their occurrence and size decreased as the F/U mole ratio increased. For the first time, we found the spherical structures in cured UF resins of higher F/U mole ratio of 1.4. After the acid hydrolysis, the spherical structures became a much predominant at the fracture surface. These results indicated that the spherical structures in cured UF resinswere much more resistant to the hydrolytic degradation by the acid than amorphous region.

• 한국미생물·생명공학회지
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• 제18권4호
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• pp.383-389
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• 1990

Penicillium verruculosum 섬유소 분해효소의 유도물질인 KC-flock 및 cellobiose octaacetate(COA)를 유일한 탄소원으로 포함하는 배지에서 21일간 배양하면서 배양여액 중의 섬유소 분해효소 각 성분의 활성도와 전기영동상의 단백질 양상을 검토하였다. 배양여액의 중의 총단백질 생성 및 섬유소 분해활성의 유도 효과는 COA 배지가 다른 두 배지의 3배 이상이었다. 배양기간의 증가에 따라 배양여액 중의 총단백질량이 증가되었는데 CMC 분해활성이나 $\beta$-glucosidase 활성의 증가보다는 avicel 분해활성도의 증가가 총단백질량의 증가와 유사하다.