• Journal of the Korean Wood Science and Technology
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• 제41권1호
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• pp.1-11
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• 2013

본 연구에서는 은수원사시나무의 산 당화공정에서 생성되는 고형 부산물의 화학적, 구조적 특성을 관찰하였다. 산 가수분해는 황산과 염산을 사용하였고, 1차 가수분해농도를 72%, 36%, 18%로 변화를 주었고, 2차 가수분해에서 4%로 동일하게 희석하였다. 가수분해 후 액상 가수분해액과 고형 부산물을 각각 분리하였고 고형 부산물을 각각 RS72, RS36, RS18, RC36, RC18이라고 하였다. 황산의 농도가 높아짐에 따라 생성된 고형부산물은 감소(71.2~21.4%)하였지만, 염산의 농도는 고형 부산물의 생성량(65.0~67.0%)에 큰 영향을 주지 않았다. 또한 RS36과 RS18은 고형 부산물 질량 대비 23.6%, RC36과 RC18은 각각 25.6%, 27.3%가 리그닌으로 이루어져 있었다. 고형 부산물의 열분해산물 분석 결과 Levoglucosan, Furfural 등 탄수화물 유래 물질과 리그닌 유래 물질인 Guaiacol, Syringol 등이 검출되었지만 RS72에서는 리그닌 유래 물질만이 검출되었다. 또한 열중량분석결과 고형 부산물 내 리그닌 함량이 높아질수록 다량의 탄이 생성되고 최대 중량 감소율이 감소하여 염산에 비해 황산이, 또한 산의 농도가 높을수록 화학적으로 축합된 구조를 형성하는 것을 확인하였다.

• Mass Spectrometry Letters
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• 제10권3호
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• pp.79-83
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• 2019

Horse heart myoglobin (MYG) and bovine serum albumin (BSA) were hydrolyzed by microwave-assisted weak-acid hydrolysis for 10, 20, 30, 40, 50, and 60 min using 2% formic acid (FA) at $100^{\circ}C$. Generally, the number of identified peptides increased with increasing irradiation time, indicating that the duration of microwave irradiation is linked to the efficiency of hydrolysis. For MYG, irradiation for 60 min provided the highest number of identified peptides, the greatest sequence coverage values and the highest MASCOT score values among the investigated irradiation times. Irradiation of BSA for 50 min, however, yielded a greater number of peptides than irradiation for 60 min due to the generation of miscleaved peptides after microwave irradiation for 50 min.

• Korean Chemical Engineering Research
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• 제56권4호
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• pp.542-546
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• 2018

본 연구에서는 해양 거대조류 중 홍조류에 속하는 꼬시레기(Gracilaria verrucosa)로부터 malonic acid를 사용하여 열수 전처리 조건(전처리 온도, 촉매 농도, 고액비, 전처리 시간)에 따른 전처리와 효소가수분해를 통한 바이오슈거(환원당) 생산 가능성을 조사하였다. 300 mM malonic acid, 1:20 고액비 조건에서 $130^{\circ}C$에서 60분간 전처리를 수행하여 49.2%의 환원당 수율을 얻었다. 전처리 반응 후 이어진 효소 가수분해를 통하여 64.5%의 수율을 확보하였다.

• 한국군사과학기술학회지
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• 제2권1호
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• pp.73-81
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• 1999

Four bis-iodosobenzoic acid derivatives have been synthesizd in 5 steps following literature methods from 5-hydroxyantranilic acid; 1) diazotization and iodination, 2) acid protection, 3) tosylate substitution, 4) acid deprotection, 5) oxidation of iodo-substituent to iodoso group. Catalytic effects of new 5,5'-tri-, tetra-, deca-, polyethyleneglycoxy- bis(2-iodosobenzoic acid) on hydrolysis reactions of PNPDPP(p-nitrophenyl diphenyl phosphate), sarin and soman have been measured to determine the role of ethyleneglycoxy substituents as phase transfer catalysts. At $25{\pm}0.2^{\circ}C$, pH 8.0, and cetyltrimethyl ammonium chloride(CTACl) micelle solution condition, bis-IBA derivatives hydrolyzes PNPDPP with maximum pseudo-first order rate constant($K_{obsd}^{max}$) of 0.32035 ~ 0.13659 $sec^{-1}$, which corresponds to 2~18 times rate increase than those of unsubstituted o-IBA[iodosobenzoate($K_{obsd}^{max}=0.0645sec^{-1}$), iodoxybenzoate ($K_{obsd}^{max}$ = $0.0178 sec^{-1}$)]. At the similar condition for PNPDPP hydrolysis, bis-IBA derivatives also act as efficient catalysts for hydrolytic cleavage of nerve agents such as sarin and soman. Hydrolysis rate constant with 5,5'-polyethyleneglycoxy- bis(2-iodosobenzoic acid) shows 7 times increase than that of simple 5-hydroxy-2-iodosobenzoic acid.

• Korea-Australia Rheology Journal
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• 제17권2호
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• pp.79-85
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• 2005

Aqueous mixtures of hyaluronic acid and poly(vinyl alcohol) system and hydrogels thereof were introduced to obtain new bioartificial materials that have excellent mechanical properties, biocompatibility and enhanced rheological properties. The interactions between hyaluronic acid and poly(vinyl alcohol) and/or borax were investigated by rheological measurements. Preparation parameters of the aqueous mixtures were mixture composition, the degree of hydrolysis of poly(vinyl alcohol) and borax concentration. From the rheological behavior, it could be deduced that the key factor of the interaction between hyaluronic acid and poly(vinyl alcohol) was the hydrogen bonding between them and the effect was pronounced with borax. Enhanced viscosity was observed at the composition of $20wt\%$ of hyaluronic acid solution and $80wt\%$ of poly(vinyl alcohol) and borax solution. Rheological properties were influenced by the degree of hydrolysis of poly(vinyl alcohol) and borax concentration. As the degree of hydrolysis and borax concentration increased, rheological properties increased due to the increased hydrogen bonding and networking of hyaluronate aggregates. Physical hydrogels from hyaluronic acid and poly(vinyl alcohol) were prepared and the composition dependence of the gels was rheologically investigated as well.

• 한국표면공학회지
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• 제53권3호
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• pp.87-94
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• 2020

Herein, sulfonated carbon nanotubes (CNT) have been prepared in dilute sulfuric acid (H₂SO₄) via a novel sulfonation approach based on gas-liquid interfacial plasma (GLIP) at room temperature. The sulfonic acid groups and total acid groups densities of CNT after GLIP treatment in 2 M H₂SO₄ for 45 min can reach to 0.53 mmol/g and 3.64 mmol/g, which is higher than that of sulfonated CNT prepared under 0.5 M / 1 M H₂SO₄. The plasma sulfonated CNT has been applied as catalysts for the conversion of microcrystalline cellulose to glucose. The effect of hydrolysis temperature and hydrolysis time on the conversion rate and product distribution have been discussed. It demonstrates that the total conversion rate of cellulose increasing with hydrolysis temperature and hydrolysis time. Furthermore, the GLIP sulfonated CNT prepared in 2 M H₂SO₄ for 45 min has shown high catalytic stability of 85.73 % after three cycle use.

• 대한화학회지
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• 제68권3호
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• pp.139-145
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• 2024

This study aims to elucidate the mechanism involved in the hydrolysis of the hexacyanoferrate(III) complex ion (Fe(CN)₆^3-) and the mechanism leading to the formation of Prussian blue (Fe^III₄[Fe_II(CN)₆]₃·xH₂O, PB) in acidic aqueous solutions at moderately elevated temperatures. Hydrolysis constitutes a crucial step in generating PB through the widely used single-source or precursor method. Recent PB syntheses predominantly rely on the single-source method, where hexacyanoferrate(II/III) is the exclusive reactant, as opposed to the co-precipitation method employing bare metal ions and hexacyanometalate ions. Despite the widespread adoption of the single-source method, mechanistic exploration remains largely unexplored and speculative. Utilizing UV-vis spectrophotometry, negative-ion mode liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), and a devised reaction, this study identifies crucial intermediates, including aqueous Fe^2+/3+ ions and hydrocyanic acid (HCN) in the solution. These two intermediates eventually combine to form thermodynamically stable PB. The findings presented in this research significantly contribute to understanding the fundamental mechanism underlying the acid-catalyzed hydrolysis of the hexacyanoferrate(III) complex ion and the subsequent formation of PB, as proposed in the sequential mechanism introduced herein. This finding might contribute to the cost-effective synthesis of PB by incorporating diverse metal ions and potassium cyanide.

• Applied Biological Chemistry
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• 제27권1호
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• pp.29-33
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• 1984

느타리버섯 재배기간(栽培期間)중 각(各) 주기별(週期別)로 채취(採取)한 퇴비(堆肥)의 화학성분(化學成分)과 산가수분해조건(酸加水分解條件)을 검토(檢討)한 결과 퇴비(堆肥)의 화학성분(化學成分)중에서 회분량(灰分量)은 재배기간(栽培期間)중에 증가(增加)되었으나 유기물(有機物)은 감소(減少)되었으며 버섯의 수량(收量)은 90% 이상이 1,2주기(週期)에서 얻어졌다. 산가수분해(酸加水分解)의 최적조건(最適條件)은 $H_{2}SO_{4}$ 2.0%, 증기압(蒸氣壓) $1.5kg/cm^{2}$, 분해시간(分解時間) 30분(分), 산첨가량(酸添加量) 20배량(倍量)에서 가장 양호하였다. furfural의 함량(含量)은 산농도(酸濃度)의 증가(增加)에 따라 현저하게 증가(增加)되었다.

• 펄프종이기술
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• 제29권4호
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• pp.18-27
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• 1997

This study was performed to obtained the optimal delignified condition of exploded wood on the acid hydrolysis with sulfuric acid. Wood chips of pine wood(Pinus desiflora), oak wood(Quercus serrata) and birch wood (Betula platyphylla var. japonica) were treated with a high pressure steam (20-30kgf/$\textrm{cm}^2$, 2-6 minutes). The exploded wood was delignified with sodium hydroxide and sodium chlorite, and then hydrolyzed with sulfuric acid. The result can be summerized as follows ; In the exploded wood treated with sodium hydroxide, the optimal concentration of sodium hydroxide was 1% as content of lignin in the exploded wood. Lignin content of exploded wood treated with sodium chlorite was lower then that sodium hydroxide. The maximum reducing sugar yield of exploded wood treated with 1% sodium hydroxide was lower than non-treated exploded wood. In the case of sodium chlorite treated, the maximum reducing sugar yield was hgher than non-treated exploded wood. Sugar composition of acid hydrolysis solution was composed of xylose and glucose residue, and the rate of glucose residue was increased in high pressure condition.

• 약학회지
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• 제42권1호
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• pp.39-45
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• 1998

Kojic acid, antimelanogenic agent, has been widely used in cosmetics to lighten the skin color. However, it has skin irritancy and instability against pH, temperature and light. To overcome these problems and optimize the molecular structure of kojic acid (KA), a prodrug, kojic acid monostearate(KMS), has been synthesized to modify the topical drug delivery in the point of sustained release of the parent drug via enzymatic hydrolysis during skin absorption. The prodrug was tested for enzymatic hydrolysis with cytosolic fraction of hairless mouse, skin. From the in vitro skin permeation study through hairless mouse skin, we found that KMS was retained in the skin and generated KA continuously by the skin esterase cleavage. In addition, topical formulations of o/w type creams and polyolprepolymer-containing cream were further tested for whitening effects using in vivo yellow skin guinea pig model.