• Restorative Dentistry and Endodontics
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• 제34권3호
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• pp.223-231
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• 2009

본 연구는 인레이 와동에서 인상을 채득하기 전 지각과민처리제 (Isodan)과 2단계 전부식 접착시스템 (One-Step)과 단일단계 자가부식 접착시스템 (All-Bond SE)으로 처리한 후, 복합레진 인레이를 자가 접착형 레진시멘트인 BisCem으로 합착시키는 경우 레진 인레이의 상아질에 대한 미세인장결합강도와 주사현미경적인 분석을 통하여 비교하였다. 본 연구의 결과, 지각과민처리제인 Isodan만을 사용하는 경우 레진 인레이의 결합강도를 감소시킬 수 있으므로 단독 사용보다는 단일 단계 자가부식 시스템 (All-Bond SE)과 같이 사용하는 것이 추천된다.

• Restorative Dentistry and Endodontics
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• 제35권6호
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• pp.486-491
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• 2010

연구목적: 이 연구의 목적은 2% 클로르헥시딘 적용이 한 단계 자가부식접착제를 이용한 직접 복합 레진 수복의 미세 인장 강도에 미치는 영향을 평가하는 것이었다. 연구 재료 및 방법: 24개의 발거된 대구치를 사용하여 3종류의 한 단계 자가부식접착제 (Clearfil $S^3$ Bond, Xeno V, G-Bond) 를 클로르헥시딘을 적용한 그룹과 적용하지 않은 그룹, 총 6개의 그룹으로 나누었다. 클로르헥시딘을 적용하거나 적용하지 않고 그 상부에 각각의 접착제를 적용하고 광중합 복합 레진으로 수복하였다. 24시간 동안 실온의 증류수에 보관한 후 각 그룹당 10개의 시편을 준비 하여 모든 시편의 미세인장 결합 강도를 측정하였다. 결과: 2% 클로르헥시딘 적용이 한 단계 자가부식접착제를 이용한 복합레진 수복의 미세인장 결합강도에 영향을 미치지 않았다. 클로르헥시딘 적용과 상관없이 Clearfil $S^3$ Bond가 가장 높은 미세인장 결합강도 값을 나타내었고 그 다음은 GBond, Xeno V 순이었다. 파절 양상은 대부분 접착성 파절을 보였고 일부는 응집성 파절을 보였다. 결론: 2% 클로르헥시딘 적용이 한 단계 자가부식접착제를 이용한 복합레진 수복의 미세인장 결합강도에 영향을 미치지 않았다.

• 농약과학회지
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• 제14권3호
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• pp.183-190
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• 2010

수용체 접근 방법으로 새로운 제초성 물질을 탐색하기 위하여 acetyl-CoA carboxylase(PDB code: 3K8X)에 대한 2-(4-(6-chloro-2-benzoxazolyl)oxy)phenoxy-N-phenylpropionamide 유도체(1-38)의 분자도킹으로부터 기질분자와 수용체 사이의 상호작용을 정량적으로 검토하였다. 대부분의 기질분자들은 ACCase의 반응점내 아미노산 잔기들(Ala1627 및 Ile1735) 사이에 2개의 수소결합이 생성되었다. 그러나 $R_1$=Acetyl 지환체(6 및 P9)와 같은 기질분자들은 나머지 잔기(Gly1998)를 포함하는 3개의 아미노산 잔기내 수소결합 주게들과 기질분자의 수소결합 받게들 사이에 3개의 수소결합이 생성되었다. 그러므로 수소결합 특성들에 기인한 기질분자들의 ACCase에 대한 저해활성 요소들은 제초성 물질을 최적화하는데 적용될 수 있을것이다.

• 대한치과보철학회지
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• 제39권3호
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• pp.260-272
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• 2001

All-ceramic restorations have had a more limited life expectancy than metal ceramic restorations because of their low strength. Their relatively lower strength and resistance to fracture have restricted the use of all-ceramic crowns to anterior applications where occlusal loads are lower. But there has been increasing interest in all-ceramic restorations because patients are primarily concerned with improved esthetics. Many efforts have been made to in prove the mechanical properties of dental ceramics. This study was designed to elucidate the influence of the luting agent on the strength of the Empress 2 crown (staining technique) cemented on human teeth. Seventy extracted human permanent molar teeth were chosen. Teeth were prepared for Empress 2 crowns with milling machine on a surveyor. A dental bur was placed in the mandrel that was positioned so that the long axis of the bur was perpendicular to the surveyor base. Dimensions of the Empress 2 crown preparation were $6^{\circ}$ taper on each side, $1.5{\pm}0.1mm$ shoulder margin, and 4mm crown height. The luting cements used in this study were as follow: 1. Uncemented 2. Zinc phosphate cements (Confi-Dental) 3. Conventional glass ionomer cement : Fuji 1 (GC) 4. Resin-modified glass ionomer cements : Fuji plus (GC) 5. Adhesive cements : Panavia F (Kuralay), Variolink II (Vivadent), Choice (Bisco). Fracture test using Instron. The crowns were loaded in compressive force to evaluate the effect of these cements on the breaking strength of these all-ceramic crowns. A steel ball with a diameter of 4mm was placed on the occlusal surface and load was applied to the steel ball by a cylindrical bolt with a crosshead speed of 0.5mm per minute until fracture occurred. The fractured surface was examined using Scanning Electron Microscopic Image (SEM) to discover the correlation between fracture strength and bonding capacity. Within the limitation of this in vitro study design, the results were as follows : 1. fomentations significantly increased the fracture resistance of Empress ceramic crowns compared to control. Uncemented (206.9 N): ZPC (812.9 N): Fuji 1 (879.5 N): Fuji Plus (937.7 N): Choice (1105.4 N): Variolink II (1221.1 N): Panavia F (1445.2 N). 2. Resin luting agent, treated by a silane bond enhancing agents, yielded a significant increase in fracture resistance. In some of the Panavia F group, a fracture extended into dentin. 3. According to SEM images of fractured Empress crowns, the stronger the bond at both interfaces(crown and die), the more fracture strength was acquired.

• Molecules and Cells
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• 제41권4호
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• pp.331-341
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• 2018

L-pipecolic acid is a non-protein amino acid commonly found in plants, animals, and microorganisms. It is a well-known precursor to numerous microbial secondary metabolites and pharmaceuticals, including anticancer agents, immunosuppressants, and several antibiotics. Lysine cyclodeaminase (LCD) catalyzes ${\beta}$-deamination of L-lysine into L-pipecolic acid using ${\beta}$-nicotinamide adenine dinucleotide as a cofactor. Expression of a human homolog of LCD, ${\mu}$-crystallin, is elevated in prostate cancer patients. To understand the structural features and catalytic mechanisms of LCD, we determined the crystal structures of Streptomyces pristinaespiralis LCD (SpLCD) in (i) a binary complex with $NAD^+$, (ii) a ternary complex with $NAD^+$ and L-pipecolic acid, (iii) a ternary complex with $NAD^+$ and L-proline, and (iv) a ternary complex with $NAD^+$ and L-2,4-diamino butyric acid. The overall structure of SpLCD was similar to that of ornithine cyclodeaminase from Pseudomonas putida. In addition, SpLCD recognized L-lysine, L-ornithine, and L-2,4-diamino butyric acid despite differences in the active site, including differences in hydrogen bonding by Asp236, which corresponds with Asp228 from Pseudomonas putida ornithine cyclodeaminase. The substrate binding pocket of SpLCD allowed substrates smaller than lysine to bind, thus enabling binding to ornithine and L-2,4-diamino butyric acid. Our structural and biochemical data facilitate a detailed understanding of substrate and product recognition, thus providing evidence for a reaction mechanism for SpLCD. The proposed mechanism is unusual in that $NAD^+$ is initially converted into NADH and then reverted back into $NAD^+$ at a late stage of the reaction.

• 복합신소재구조학회 논문집
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• 제6권4호
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• pp.8-15
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• 2015

The demand for environmental consideration is on the increase in civil engineering. This study focuses on the development of technology to reduce the use of carbonate cement and improve its performance by using a silicate mineral and hardening agents, and presents the test results for the demonstrative evaluation of the properties of the raw material. Highly active feldspar was used as a binder to augment the bonding of the carbonate cement, and their change in strength was observed after test piece construction with the addition of soluble hardening agent. The uniaxial compression strength of the test piece of the general Portland cement with the addition of 0.5% soluble hardening agent, showed an increase by 33% and that of the test piece of cement with the addition of 70% substituted with feldspar increased by 28%. The strength of viscous soil; classified as soft ground, showed an increase of a maximum of 1.7 times when it was mixed with cement and solidifier depending on the curing period. These tests confirmed that a soluble solidifier is effective for improving the strength of a cement binder and that the highly active feldspar can be used as a binder.

• 복식문화연구
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• 제13권3호
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• pp.380-390
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• 2005

The effect of high purity chitosan was studied on its application to the natural dyeing using Rhusjara ica. In the dyeing experiment, examinations were introduced on the difference between the chitosan treated fabrics and chitosan untreated fabrics, and on the difference according to the type of mordanting agents and the mordanting methods. Dyeing was carried out for the chitosan treated and untreated fabrics under the conditions of non-mordanting and Al, Sn, Fe mordanting. As a result, we found that, in the case of cotton, chitosan untreated fabrics were not dyed enough, and the dyeing effect was not developed even though the mordanting was introduced. However, the chitosan treated fabrics developed excellent dyeing result even in the non-mordanting case. Through the results of cotton fabric dyeing, it was presumed that the dyeing affinity of the chitosan toward the Rhusjara ica, which prefer specific dyestuff (mainly black color), is selectively high. In the case of nylon, the dyeing effect is not developed easily under all conditions regardless of the chitosan treatment or the mordant treatment. It was inferred that a certain portion of the Rhusjara ica dyestuff made direct bonding with the functional elements in the nylon molecules without the help of the mordant. Through the results of nylon fabrics, it was presumed that some functional elements of the nylon molecules had selective affinity toward the specific colorant (mainly yellow color) of the Rhusjara ica.

• Archives of Pharmacal Research
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• 제24권5호
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• pp.455-465
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• 2001

The highly potent cytotoxic DNA-DNA cross-linker consists of two cyclopropa[c]pyrrolo[3,4-3]indol-4(5H)-ones insoles [(+)-CPI-I] joined by a bisamido pyrrole (abbreviated to "Pyrrole"). The Pyrrole is a synthetic analog of Bizelesin, which is currently in phase II clinical trials due to its excellent in vivo antitumor activity. The Pyrrole has 10 times more potent cytotoxicity than Bizelesin and mostly form DNA-DNA interstrand cross-links through the N3 of adenines spaced 7 bp apart. The Pyrrole requires a centrally positioned GC base pair for high cross-linking reactivity (i.e., $5^1$-T$AT_2$A*-$3^1$), while Bizelesin prefers purely AT-rich sequences (i.e., $5^1$-T$AT_4$A*-$3^1$, where /(equation omitted) represents the cross-strand adenine alkylation and A* represents an adenine alkylation) (Park et al., 1996). In this study, the high-field $^1$H-NMR and rMD studies are conducted on the 1 1-mer DNA duplex adduct of the Pyrrole where the 5′(equation omitted)TAGTTA*-3′sequence is cross-linked by the drug. A severe structural perturbation is observed in the intervening sequences of cross-linking site, while a normal B-DNA structure is maintained in the region next to the drug-modified adenines. Based upon these observations, we propose that the interplay between the bisamido pyrrole unit of the drug and central C/C base pair (hydrogen-bonding interactions) is involved in the process of cross-linking reaction, and sequence specificity is the outcome of those interactions. This study suggests a mechanism for the sequence specific cross-linking reaction of the Pyrrole, and provides a further insight to develop new DNA sequence selective and distortive cross-linking agents.

• 펄프종이기술
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• 제31권1호
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• pp.31-38
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• 1999

Adsorption of polymeric flocculants and dry strength agents onto the surface of papermaking fibers is critical for their effective utilization since the polymeric substances not adsorbed on fibers or fines keep recirculating in the papermaking system to cause various operational difficulties and loss of raw materials. Problems associated with the unadsorbed polymeric substances generate great attention because unprecedent interests in utilization of recycled papers and papermaking system closure. In this study, to understand the effects of recycling on the adsorption propensity of cationic polyacryamide (PAM) dry strength resin onto hardwood bleached kraft pulp fibers and fines a systematic approach was followed. Never dried bleached hardwood kraft pulp was recycled in two different ways. In mode one recycling experiment never dried pulp was beaten then recycled three times by employing simple drying and disintegrating steps. In mode two recycling experiment beating of the recycled pulp was carried out after each recycling step. Adsorption of cationic PAM on fibers and fines was evaluated employing Kjeldahl nitrogen analysis method. The influence of recycling on water retention value, carboxyl content, sheet density and tensile strength of the pulp was examined. As the number of recycling increased, water retention value of the fiber was reduced due to hornification and this in turn caused a decrease in adsorption of cationic PAM. On the other hand, the carboxyl content of the recycled fibers increased because of the oxidation of fibers occurred during drying, and this caused an increase in adsorption of cationic PAM. Because of these two opposing factors the adsorption of the cationic PAM on the recycled fibers decreased and then increased slightly at third recycling step. Increase of PAM adsorption, however, did not provide did not provide and strength improvement for the recycled pulp fibers indicating greater influence of the honification on interfiber bonding.

• 폴리머
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• 제25권4호
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• pp.512-520
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• 2001

섬유강화 복합재료의 물성을 결정하는 주요 인자중 하나는 계면결합력이다. 본 연구에서는 유리섬유와 PC/SAN 블렌드를 대상으로 하여 계면결합력을 측정하였으며 SAN함량을 0-30 wt%까지 변화시켜 실험하였다. 계면결합력 측정에는 Single Fiber Fragmentation Test법을 사용하였는데 SAN 함량이 증가할수록 계면결합력이 증가하였다. 한편 계면결합력을 증가시키기 위해 PC/SAN 혼련물을 개질하고자 소량의 SMA를 혼합하였으며, 유리섬유 표면을 실란 커플링제로 처리하여 관능기를 도입하였다. 계면결합력은 SAN/SMA계의 상용성에 크게 영향을 받았으며, 비상용성 SAN/SMA계보다 상용성 SAN/SMA계에서 계면결합력이 증가하였다. 또한 상용성 SAN/SMA계에서는 계면결합력이 SMA 내의 MA 함량이 아닌 전체 계내의 MA 함량에 의존하였으며 그 최적 함량은 0.4wt%였다.