• Restorative Dentistry and Endodontics
• /
• v.43 no.3
• /
• pp.18.1-18.12
• /
• 2018

Objectives: This study compared the retention of BioAggregate (BA; Innovative BioCeramix) and mineral trioxide aggregate (MTA; Angelus) as coronal plugs after applying different intracanal medications (ICMs) used in regenerative endodontic. Materials and Methods: One-hundred human maxillary central incisors were used. The canals were enlarged to a diameter of 1.7 mm. Specimens were divided into 5 groups (n = 20) according to the ICM used: calcium hydroxide (CH), 2% chlorhexidine (CHX), triple-antibiotic paste (TAP), double-antibiotic paste (DAP), and no ICM (control; CON). After 3 weeks of application, ICMs were removed and BA or MTA were placed as the plug material (n = 10). The push-out bond strength and the mode of failure were assessed. The data were analyzed using 2-way analysis of variance, the Tukey's test, and the ${\chi}^2$ test; p values < 0.05 indicated statistical significance. Results: The type of ICM and the type of plug material significantly affected bond strength (p < 0.01). Regardless of the type of ICM, BA showed a lower bond strength than MTA (p < 0.05). For MTA, CH showed a higher bond strength than CON, TAP and DAP; CHX showed a higher bond strength than DAP (p < 0.01). For BA, CH showed a higher bond strength than DAP (p < 0.05). The mode of failure was predominantly cohesive for BA (p < 0.05). Conclusions: MTA may show better retention than BA. The mode of bond failure with BA can be predominantly cohesive. BA retention may be less affected by ICM type than MTA retention.

• YAKHAK HOEJI
• /
• v.50 no.1
• /
• pp.40-46
• /
• 2006

Square wave voltammetric (SWV) and cyclic voltammetric (CV) behaviors of cefotaxime sodium and ceftriaxone sodium have been investigated in the potential range between -0.10 V and -1.30 V using the phosphate buffers of various pH values ($2.00{\sim}9.10$). Two main peaks observed were irreversible and protons were involved in their electrochemical reductions. The first peaks of these cephalosporin antibiotics are due to the reduction of the azomethine double bond in the methoxyimino group of the side chain at position 7. The second peaks of cefotaxime sodium and ceftriaxone sodium are related to the reductions of the ${\Delta}^3$ double bond and the dioxo moiety of the side chain at position 3, respectively. The calibration curve of cefotaxime sodium in the concentration range between $1.0{\times}10^{-7}M$ and $1.0{\times}10^{-5}M$ yielded the linearity with the correlation coefficient of 0.9998 when the first peak of the antibiotic in a phosphate buffer of pH 3.02 was measured at the conditions of frequency of 120 Hz and pulse height of 50 mV by SWV. The present fast, simple and accurate SWV assay method was applied to determine cefotaxime sodium in the commercial antibiotic powder of injection.

• Journal of the Korean Applied Science and Technology
• /
• v.7 no.2
• /
• pp.33-40
• /
• 1990

The Kinetics of the addition of benzalacetophenone derivatives was investigated by ultraviolet spectrophotometery in 5% dioxane $H_2O$ at $50^{\circ}C$. A rate equation was obtained in wide range of pH. The substituent effects on benzalacetophenone derivatives were studied, and addition were facilitated by electron attracting groups. The final product was benzalacetophenone-${\beta}$-thioglycolic acid synthesized by the addition of thioglycolic acid to benzalacetophenone. On the base of the rate equation, substituent effect, general base effect and final product, the plausible addition mechanism was proposed: Below pH 9.0, only neutral thioglycolic acid molecule was added to the carbon-carbon double bond, and in the range of pH $9.0{\sim}11.0$, neutral thioglycolic acid molecule and thioglycolic acid anion competitively attacted the double bond. By contrast, above pH 11.0, the reaction was dependent upon only the addition of thioglycolic acid anion.

• Journal of the Korean Chemical Society
• /
• v.39 no.5
• /
• pp.338-343
• /
• 1995

The electronic structure of photoskinsensitizing 8-azapsoralen and 4,4',5'-trimethyl-8-azapsoralen has been investigated by the semiempirical (PM3-CI-UHF, etc) methods. The formation of molecular complexes between ground thymine and excited azapsoralen is discussed in terms of charge transfer interaction. The results indicated that the most probable orientation through C4-cycloaddition of 3,4-double bond of azapsoralen and 5,6-double bond of thymine bases, expecially photoadducts were inferred to be a trans-anti azapsoralen(3,4) < > Thymine(5,6) and trans-anti 4,4',5'-trimethyl-8-azapsoralen (3,4) < > Thymine(5,6).

• Journal of the Korean Applied Science and Technology
• /
• v.14 no.1
• /
• pp.27-32
• /
• 1997

Furfurylidene acetophenone derivatives were synthesis, it was measured that nucleophilic addition made use of UV at a wide pH 1.0${\sim}$13.0 range in 30% dioxane-$H_2O$ solution, 25$^{\circ}C$. On the basis of general base catalysis, substitutent effect, confirmation of nucleophilic addition products, it was measured the reaction rate of furfurylidene acetophenone derivatives for the pH change. It may be concluded that a part was unrelated to pH and another part was in proportion to concentration of hydroxide ion: Above pH 10.0. sulfide anion adds to the double bond (Michael type addition), a part having no concern with pH, addition reaction to double bond is initiated by addition of neutral thiourea molecule. From the result of measurement the reaction rate, nucleophilic addition of furfurylidene acetophenone derivatives confirmed to the irreversible first order. Through measurement the substituent effect. It found that reaction rate was accelerated by electron attracting group. On the basis of these findings, nucleophilic addition of thiourea for the furfurylidene acetophenone derivative was proposed a fitting mechanisms.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.12
• /
• pp.4131-4136
• /
• 2012

Several palladium complexes containing ${\beta}$-ketoiminate and ${\beta}$-diketiminate ligands successfully produced poly(DCPD) possibly via vinyl addition. It was found that catalysts with ${\beta}$-diketiminate ligands containing bulkier aryl substituents showed the highest activity in the presence of MAO as a cocatalyst. Purity of DCPD is quite essential for the higher activity and small amount of organic solvent such as $CH_2Cl_2$ and toluene is required to reduce the viscosity of the reactant mixture for the higher activity. $^1H$ NMR spectra of produced polymers with N,N-dimethylanilinium tetra(pentafluorophenyl)borate (N,N-DAPFAr"$_4$) show that 5,6-double bond of DCPD is removed with 2,3-double bond remaining. Produced poly(DCPD) with MAO cocatalyst is quite rigid and insoluble in common organic solvents but rather brittle.

• Journal of the Korean Applied Science and Technology
• /
• v.8 no.2
• /
• pp.175-181
• /
• 1991

The kinetics of the addition of 1-benzylindole-3-(p-substituted) acetophenone derivatives was investigated by ultraviolet spectrophotometery in 30% dioxane -$H_2O\;at\;25^{\circ}C$. A rate equation which can be applied over wide pH range was obtained. The Substituent effects on 1-benzylindole-3-(p-substituted) acetophenone derivatives were studied, and addition were facilitated by electron attracting groups. On the base of the rate equation, substituent effect, and general base effect the plausible addition mechanism was proposed : Below pH 3.0, only neutral thiourea molecule was added to the carbon-carbon double bond, and in the range of pH 0.0${\sim}$14.0, netural thiourea molecule and thiourea anion competitively attacted the double bond. By contrast, above pH 10.0, the reaction was dependent upon only the addition of thiourea anion.

• Bulletin of the Korean Chemical Society
• /
• v.15 no.1
• /
• pp.53-57
• /
• 1994

A comparison study on asymmetric borane reduction of ketoxime ethers and N-substituted ketimines possesing C = N double bond mediated by the selected chiral oxazaborolidines (1-6) was investigated. Thus, an aromatic ketoxime O-alkyl ether acetophenone oxime O-methyl ether was reduced to the corresponding amine (1-phenylethylamine 8a) with optical yields, such as 58% ee with 1, 86% ee with 2, 3% ee with 3, 99% ee with 4, 60% ee with 5, and 73% ee with 6. However, the reduction of an aliphatic ketoxime derivative 2-heptanone oxime O-methyl ether provided low optical inductions (7-13% ee). For ketoxime O-trimethylsilyl ethers, the reduction of acetophenone O-trimethylsilyl ether afforded 8a with optical yields which were 90% ee with 1, 40% ee with 2, 2% ee with 3, 62% ee with 4, 5% ee with 5, and 60% ee with 6. The reduction of 2-heptanone O-trimethylsilyl ether also gave the product amine with low optical yields (10-40% ee). In the case of N-substituted ketimines, the reduction of acetophenone N-phenylimine afforded the corresponding amine with 79% ee, 78% ee, 9% ee, 73% ee, 78% ee and 67% ee using 1, 2, 3, 4, 5, and 6, respectively, whereas low optical inductions (5-18% ee) for 2-heptanone N-phenylimine were achieved.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.10
• /
• pp.1177-1180
• /
• 1999

The ab initio SCF MO and density functional theory (DFT) studies are carried out on the electrophilic (1a) and electron transfer (1b) addition reactions to the vinyl double bond of aryl vinyl sulfides and ethers. In the electrophilic addition processes, a double bond shift from C3 = C4 to X = C3 occurs with occupation number (1.97) close to the normal two. Due to this shift direct conjugation between the cationic center, X = S or O, and the para electron-donor substituent becomes impossible so that the reaction energies (or log K) are correlated with σ rather than σ+. By contrast, radical cation formation leads to delocalization of the SOMO, a lone-pair πorbital on X, with four major resonance structures in which cationic charge as well as spin density is delocalized over C4 , X and C7 atoms. As a result, partial πbonds are formed over C1 -X and C3 - C4 with occupation numbers (0.82) lower than one. In two of the cannonical structures, III(Ⅹ) and III(X+), direct conjugation between the cationic center, X, and the para substituent is achieved so that a better correlation with σ+ rather than σis obtained. The SCF MO energies at the HF/3-21G* and HF/6-31G* levels lead to very much inferior Hammett correlations in the σ/ σ+ diagnostic criterion. In contrast, the ρvalues evaluated with the DFT energies can give reliable diagnostic distinction between the two addition mechanisms.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.11
• /
• pp.2500-2504
• /
• 2011

Living organisms are composed of cells that can replicate themselves through growth, division packed with tons capacity. On DNA mutations, ie mutations in the offspring's survival and reproduction can be held against you, and packed with tons ambivalence that could benefit. In this study, the DNA double helix is used as a template for replication, we first separated into single strands of the double helix must be opened Combining the double helix portion of the location of errors in the bond provides a way to find and repair.