• Archives of Pharmacal Research
• /
• 제19권3호
• /
• pp.191-196
• /
• 1996

Bizelesin is a promising novel anticancer agent which is known to alkylate N3 of adenine to induce DNA interstrand cross-links (ISC) with in $5^I-TAATTA\; and\; 5^I-TAAAAAA$. We have investigated the base specificity for DNA ISC induced by bizelesin using oligomers containing the cross-linkable sequence $5^I-TAATTA\; and\; 5^I-TAAAAAA$. in which "N" was either A, C, G, or T. An analysis of denaturing polyacrylamide gel showed that bizelesin is able to induce DNA ISC in the duplex oligomer containing sequences $5^I-TAATTA\; and\; 5^I-TAAAAAA$. The formation of interstrand crosslinking did not occur in the sequences $5^I-TAATTA\; and\; 5^I-TAAAAAA$. DNA strand cleavage assay to determine the cross-linking site within $5^I-TAATTA$sequence showed that bizelesin alkylates guanine. These results demonstrate that bizelesin is able to induce DNA ISC at guanine but not at cytosine or thymine. In addition, guanine adducts have been found to be susceptible to DNA strand cleavage by exposure to hot piperidine. The extent of DNA strand cleavage, however, was not 100% efficient in either neutral pH buffer or hot piperidine.

• 한국응용과학기술학회지
• /
• 제18권2호
• /
• pp.142-152
• /
• 2001

Acrylic resin(ACR) was blended with a curing agent, hexamethoxymethylmela-mine(HMMM), in which blending ratio was 70:30. The curing behavior was examined using Rheovibron. Cross-linking reaction started at $170^{\circ}C$ in 2 min of reaction and curing was completed in 10 min. It was found that the extent of cross-linking increased with the content of acetoacetoxyethyl methacrylate monomer in the ACR.

• Bulletin of the Korean Chemical Society
• /
• 제22권12호
• /
• pp.1293-1294
• /
• 2001

• 한국안광학회지
• /
• 제19권2호
• /
• pp.145-151
• /
• 2014

목적: 개시제와 교차결합제의 농도에 따른 소프트콘택트렌즈의 재질을 변화시켜서 재질변화에 대한 물리적 특성 및 약물의 용출량 및 속도를 비교하였다. 방법: HEMA에 개시제인 AIBN과 교차결합제인 EGDMA의 농도을 변화시켜서 콘택트렌즈를 제작하였다. 항균물질인 노플록사신(norfloxacin)은 고분자 중합 시 0.1% 농도로 단량체와 함께 혼합하였다. 재질변화에 따른 물리적 성질 변화를 확인하기 위해 약물용출 농도, 함수율, 굴절률, 단백질 흡착량 등에 대한 실험을 통하여 비교하였으며, 통계분석을 통해 유의성을 확인하였다. 결과: 개시제의 농도을 변화 시킨 콘택트렌즈는 함수율의 변화가 거의 없으며, 굴절률의 값에도 별 변화가 없었다. 교차결합제 농도이 증가하면 함수율이 낮아지고 굴절률이 높아졌다. 약물용출의 농도를 살펴보면 개시제의 변화에 의해서는 많은 변화를 보이지 않았으며, 함수율이 높을수록 용출되는 농도가 증가하였다. 단백질 흡착양은 개시제에 의한 변화는 거의 없었으며 함수율이 낮을수록 흡착되는 양이 증가하였다. 결론: 개시제의 농도에 대한 변화는 특성 변화에 영향력이 거의 없었으며, 교차결합제 농도에 따라서는 많은 변화를 보였다. 교차결합제의 농도가 증가할수록 함수율은 감소하며 굴절률은 증가하였다. 또한 함수율의 증가에 따라 약물이 많이 용출되었으며 단백질의 흡착량은 감소되었다.

• 펄프종이기술
• /
• 제43권4호
• /
• pp.49-58
• /
• 2011

The maximum drying shrinkage velocity was proposed to verify bulk and stiffness improvement mechanism during drying according to papermaking parameters. It was based on the wet-web shrinkage behavior without the restraint of wet-web during drying, so intact drying impact could be measured. Bulking agent reduced the drying shrinkage and the maximum drying shrinkage velocity, so paper bulk increased and paper strength decreased. When adding cationic starch to stock with the bulking agent for strengthening, the bulk was increased further with additional decreasing of the drying shrinkage and the maximum drying shrinkage velocity. Paper strength also increased except tensile stiffness index with decreasing the drying shrinkage and the maximum drying shrinkage velocity. When using additional strength additives for strengthening of fiber interfaces extended by bulking agent and cationic starch, amphoteric strength additive increased paper stiffness without loss of paper bulk. It was considered that the added amphoteric strength additives were cross-linked to the stretched cationic starch and this cross-linking increased elasticity of fiber-polymer-fiber interfaces without changing the drying behavior. Paper bulk could be increased with decreasing the maximum drying shrinkage velocity. The drying shrinkage of paper also could be controlled by fiber-to-fiber bonding interfaces by the bulking agent. In this case, paper strength including stiffness was decreased by reducing fiber-to-fiber bonding but it could be improved by strengthening fiber-to-fiber interfaces with polymer complex without loss of bulk.

• Journal of Applied Biological Chemistry
• /
• 제59권1호
• /
• pp.75-81
• /
• 2016

Glutaraldehyde was used as a cross-linking agent for immobilization of purified ${\alpha}$-amylase from Exiguobacterium sp. DAU5. Befitting concentration of glutaradehyde and cross-linking time is the key to preparation of cross-linking chitosan beads. Based on optimized immobilization condition for ${\alpha}$-amylase, an overall yield of 56% with specific activity of 2,240 U/g on chitosan beads and 58% with specific activity of 2,320 U/g on chitosan-carbon beads was obtained. The optimal temperature and pH of each immobilized enzyme activity were $50^{\circ}C$ and 50 mM glycine-NaOH buffer pH 8.5, respectively. Those retained more than 75 and 90% of its maximal enzyme activity at pH 7.0-9.5 and after incubation at $50^{\circ}C$ for 1 h, respectively. In addition, the immobilization product showed higher organic-solvent tolerance than free enzymes. The mode of hydrolyzing soluble starch revealed that the ${\alpha}$-amylase possessed high hydrolyzing activity. These results indicate that chitosan is good support and has broad application prospects of enzyme immobilization.

• Bulletin of the Korean Chemical Society
• /
• 제16권4호
• /
• pp.360-363
• /
• 1995

The photopolymerization of methyl methacrylate(MMA) with phenylsilane wasperformed. The molecular weights of the poly(MMA) containing SiH moieties were increased with augment of molar ratio of PhSiH3 over MMA by cross-linking via hydrosilation at the expense of isolated yield. Phenylsilane apparently influenced on the photopolymerization as a chain transfer agent and solvent.

• 접착 및 계면
• /
• 제12권2호
• /
• pp.73-80
• /
• 2011

식물성 고분자인 대두단백질을 기반으로 하는 환경친화성 고분자 신소재에 관한 연구를 위해 가소제(1,3-propandiol, glycerol) 및 가교제(glutaraldehyde, epichlorohydrin, glyoxal, urea)에 의한 대두단백질 수지의 열적 특성을 TGA를 이용하여 분석하였고, 기계적 특성 분석과 SEM을 통하여 파단면을 관찰하였다. 그 결과, 가소제인 1,3-propandiol과 glycerol을 SPI (대두단백질)에 첨가함으로써 수지의 유연성이 증가하였고, 1,3-propandiol에 비하여 glycerol의 가소화 효과가 상대적으로 크게 나타났으며, 가교제인 glycerol, epichlorohydrin, glyoxal의 적용으로 첨가량이 증가할수록 대두단백질 수지의 강도와 열안정성이 증가하는 반면, urea의 경우, 대두단백과의 가교가 용이하지 않아 열안정성이 오히려 낮아지고, 강도가 감소함을 알 수 있었다.

• Preventive Nutrition and Food Science
• /
• 제12권2호
• /
• pp.122-125
• /
• 2007

Gelidium corneum films were prepared using cinnamaldehyde as a cross-linking agent and their physical properties were determined. Tensile strength (TS) value of the film containing 0.01% cinnamaldehyde was higher than the control by 8.31 MPa. However, increasing cinnamaldehyde from 0.01% to 0.1% significantly decreased TS from 9.54 MPa to 0.03 MPa, and no film was formed at 1% cinnamaldehyde. On the contrary, when cinnamaldehyde content was increased from 0.01% to 0.1%, % elongation was increased from 1.44% to 2.75%. Water vapor permeability (WVP) of the film containing 0% and 0.01% cinnamaldehyde were 1.64 ng m/m$^2$sPa and 1.42 ng m/m$^2$sPa, respectively. There was no significant difference in Hunter values among treatments. Scanning electron microscopy results revealed that both cinnamaldehyde and control films had similar surfaces. These results suggest that 1.5% Gelidium corneum treated with 0.01% cinnamaldehyde should be the most suitable condition for film formation.

• Restorative Dentistry and Endodontics
• /
• 제37권1호
• /
• pp.2-8
• /
• 2012

The limited durability of resin-dentin bonds severely compromises the longevity of composite resin restorations. Resin-dentin bond degradation might occur via degradation of water-rich and resin sparse collagen matrices by host-derived matrix metalloproteinases (MMPs). This review article provides overview of current knowledge of the role of MMPs in dentin matrix degradation and four experimental strategies for extending the longevity of resin-dentin bonds. They include: (1) the use of broadspectrum inhibitors of MMPs, (2) the use of cross-linking agents for silencing the activities of MMPs, (3) ethanol wet-bonding with hydrophobic resin, (4) biomimetic remineralization of water-filled collagen matrix. A combination of these strategies will be able to overcome the limitations in resin-dentin adhesion.