• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1064-1069
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• 1994

Chlorobis(isoprene)rhodium(Ⅰ) (3), prepared by olefin-exchange reaction of chlorobis(cyclooctene)rhodium dimer (2) with isoprene, reacted with benzaldimine 4 to give iminoacylrhodium(Ⅲ) ${\eta}^3$-1,2-dimethylallyl complex 6. Ligand-promoted reductive elimination of 6 by pyridine and P(OMe)$_3$ produced ${\beta},{\gamma}$-unsaturated ketimine 8, which was readily hydrolyzed to give ${\beta},{\gamma}$-unsaturated ketone 9. Other methyl branched dienes such as 2,3-dimethylbutadiene, 3-methyl-1,3-pentadiene, 2-methyl-1,3-pentadiene, 2,4-dimethyl-1,3-pentadiene, 3-methyl-1,4-pentadiene and 2-methyl-1,4-pentadiene, were applied the synthesis of ${\beta},{\gamma}$-unsaturated ketones. In case of 2,4-dimethyl-1,3-pentadiene, only ${\gamma},{\delta}$ -unsaturated ketone 25, 1,2-addition product, was obtained, may be due to the mono-olefin coordination.

• Bulletin of the Korean Chemical Society
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• v.19 no.12
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• pp.1355-1359
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• 1998

The treatment of 1,1-bis(phenylthio)-2,2,3,3,3-pentafluoropropylbenzene (1) with 2 equiv. of phenyllithium in THF at -78 ℃ resulted in the formation of isomeric mixture (70: 30) of trifluoromethylated 1,2-diphenylvinyl sulfide 2 in 87% yield. The further oxidation of 2 with m-chloroperbenzoic acid in methylene chloride afforded isomeric mixture (70:30) of trifluoromethylated 1,2-diphenylvinyl sulfone 3 in 87% yield. When 3 was reacted with carbon nucleophiles such as methyllithium, n-butyllithium, phenyllithium and lithium octylide, the corresponding addition-elimination adducts 4, 5, 6 and 7 were obtained in moderate to good yields. The reaction of 3 with 4 equiv. of tributyltin hydride in benzene at reflux temperature provided isomeric mixture (90 : 10) of trifluoromethylated 1,2-diphenylvinyl stannane 8 in 41% yield. The reaction of 8 with methyllithium in the presence of trimethylsilyl chloride gave isomeric mixtures (90: 10) of trifluoromethylated 1,2-diphenylvinyl silane 9 in 88% yield. Finally, the treatment of 8 with Br2 and 12 resulted in the formation of isomeric mixtures (90: 10) of trifluoromethylated 1,2-diphenylvinyl bromide 10 and iodide 11 in 72% and 90% yields, respectively.

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.573-576
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• 1999

The rate constants and kinetic solvent isotope effects (KSIE, KMeOH/kMeOD) for solvolyses of para-substituted phenylchloroformates in CH3OH, CH3OD, H2O, D2O, 50% D2O-CH3OD were determined at 15.0 and 25.0℃ using conductometric method. Kinetic solvent isotope effects for the solvolyses of para-substituted phenyl chloroformates were 2.39-2.51, 2.21-2.28, and 1.67-1.69 for methanol, 50% aqueous methanol, and water, respectively. The slopes of Hammett plot for solvolysis of para-substituted phenyl chloroformates in methanol, 50% aqueous methanol, and water were 1.49, 1.17 and 0.89, respectively. The Hammett type plot of KSIE, log (KSIE) versus p, can be a useful mechanistic tool for solvolytic reactions. The slopes of such straight lines for para-substituted phenyl chloroformates are almost zero in methanol, 50% aqueous methanol, and water. It was shown that the reaction proceeds via an associative SN2 and/or general base catalysis addition-elimination (SAN) mechanism based on activation parameters, Hammett p values, and slopes of Hammett type plot of KS-IE.

• Clinical and Experimental Pediatrics
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• v.64 no.11
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• pp.543-551
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• 2021

The human microbiome, which consists of a collective cluster of commensal, symbiotic, and pathogenic microorganisms living in the human body, plays a key role in host health and immunity. The human nasal cavity harbors commensal bacteria that suppress the colonization of opportunistic pathogens. However, dysbiosis of the nasal microbial community is associated with many diseases, such as acute respiratory infections including otitis media, sinusitis and bronchitis and allergic respiratory diseases including asthma. The nasopharyngeal acquisition of pneumococcus, which exists as a pathobiont in the nasal cavity, is the initial step in virtually all pneumococcal diseases. Although the factors influencing nasal colonization and elimination are not fully understood, the adhesion of opportunistic pathogens to nasopharyngeal mucosa receptors and the eliciting of immune responses in the host are implicated in addition to bacterial microbiota properties and colonization resistance dynamics. Probiotics or synbiotic interventions may show promising and effective roles in the adjunctive treatment of dysbiosis; however, more studies are needed to characterize how these interventions can be applied in clinical practice in the future.

• Bulletin of the Korean Chemical Society
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• v.16 no.3
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• pp.252-256
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• 1995

Semiempirical MO calculations using the PM3 method are performed on the reactions of acetate esters with substituted phenolate anions. The mechanistic change from rate-limiting formation to breakdown of the anionic intermediate is shown to occur in the gas-phase, especially for meta-nitrophenyl acetate. However the mechanistic change-over takes place at a lower basicity ($pK_0$) of the anion nucleophile than found for the corresponding formate. This lowering of $pK_0$ has been ascribed to the electron donating effect of the methyl group in the acetate. For the reactions involving rate-limiting breakdown of the intermediate, the large Bronsted coefficients, ${\beta}_X({\beta}_{nuc})$, are expected in general, but the magnitude increases to a larger value and the pK0 is lowered accordingly, when an electron-donating nonleaving group, like $CH_3$, is present. This type of nonleaving group effect provides a necessary condition for the carbonyl addition-elimination mechanism with rate-limiting breakdown of the intermediate.

• Bulletin of the Korean Chemical Society
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• v.14 no.2
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• pp.287-291
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• 1993

Catalytic iminohydroacylation has been achieved by the reaction of aldimine 1 and 1,5-hexadiene (2a) with Wilkinson's complex as catalyst. Compounds 7a, 8a and 9a were obtained as final product after hydrolysis of the resulting iminohydroacylation products 4a, 5a and 6a. Depending on the reactant ratio (2/1), the ratio of products were changed dramatically : As the 2/1 ratio was increased, 7a is the major product after hydrolysis while 8a is the major with an 1/1 ratio of 2/1. The mechanism of the formation of 5a is determined by the reaction of 1 and 2b under the identical reaction conditions. Considering that 5a may not be formed from the hydroiminoacylation of 14a since 5b cannot be formed from that of conjugate diene 14b generated from isomerization of 2b, 5a must be formed from the reaction of 4a and 10 by addition-elimination mechanism.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.983-989
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• 2008

Human insulin is a hormone well-known to regulate the blood glucose level. Recombinant preproinsulin, a precursor of authentic insulin, is typically produced in E. coli as an inactive inclusion body, the solubilization of which needs the addition of reducing agents such as $\beta$-mercaptoethanol. To make authentic insulin, recombinant preproinsulin is modified enzymatically by trypsin and carboxypeptidase B. The effects of $\beta$-mercaptoethanol on the formation of human insulin derivatives were investigated in the enzymatic modification by using commercially available human proinsulin as a substrate. Addition of 1 mM $\beta$-mercaptoethanol induced the formation of various insulin derivatives. Among them, the second major one, impurity 3, was found to be identical to the insulin B chain fragment from $Phe_1$ to $Glu_{21}$. Minimization of the formation of insulin derivatives and concomitant improvement of the production yield of human insulin were achieved by the addition of hydrogen peroxide. Hydrogen peroxide bound with $\beta$-mercaptoethanol and thereby reduced the negative effects of $\beta$-mercaptoethanol considerably. Elimination of the impurity 3 and other derivatives by the addition of over 10 mM hydrogen peroxide in the presence of $\beta$-mercaptoethanolled to a 1.3-fold increase in the recovery efficiency of insulin, compared with those for the case without hydrogen peroxide. The positive effects of hydrogen peroxide were also confirmed with recombinant human preproinsulin expressed in recombinant E. coli as an inclusion body.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.450-456
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• 2016

STDR (sequence time domain reflectometry) to detect a cable fault using a pseudo noise sequence as a reference signal, and time correlation analysis between the reference signal and reflection signal is robust to noisy environments and can detect intermittent faults including open faults and short circuits. On the other hand, if the distance of the fault location is far away or the fault type is a soft fault, attenuation of the reflected signal becomes larger; hence the correlation coefficient in the STDR becomes smaller, which makes fault detection difficult and the measurement error larger. In addition, automation of the fault location by detection of phase and peak value becomes difficult. Therefore, to improve the cable fault detection of a conventional STDR, this paper proposes the algorithm in that the peak value of the correlation coefficient of the reference signal is detected, and a peak value of the correlation coefficient of the reflected signal is then detected after removing the reference signal. The performance of the proposed method was validated experimentally in low-voltage power cables. The performance evaluation showed that the proposed method can identify whether a fault occurred more accurately and can track the fault locations better than conventional STDR despite the signal attenuation. In addition, there was no error of an automatic fault type and its location by the detection of the phase and peak value through the elimination of the reference signal and normalization of the correlation coefficient.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.4 s.48
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• pp.491-497
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• 2004

Holographic quantitative structure activity relationships (HQSAR) between the melanogenesis inhibitory activities of alkyl-3,4-dihydroxybenzoate (A) and N-Alkyl-3,4-dihydroxybenzamide (B) derivatives were analyzed and discussed. The statistical results of HQSAR model for the activities showed the best predictability of the activities based on the cross-validated $r^2_{cv}\;(q^2=0.674),$ non-cross-validated, conventional coefficient $(r^2_{ncv}=0.936).$ The melanogenesis inhibitory activities and hydrolytic reactivity of (A) were slightly higher than that of (B) (A>B) and the activities depends upon the $R_1-substituents\;(R_1>R_2).$ It has been found using frontier molecular orbital (FMO) theory that the hydrolysis reactions of (A) and (B) proceeded to an orbital-controlled reactions, while the nucleophillc addition-elimination reactions $(Ad_{N-E})$ between LUMO energy of (A) and (B) and HOMO energy of water molecule are occurred.

• Journal of Korean Medical classics
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• v.21 no.1
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• pp.111-122
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• 2008

At the book I of "The Golden Mirror of Medicine[醫宗金鑑] The Elimination and Supplement about Famous Prescription Comments[刪補名醫方論]", 22 prescriptions are recorded. At the first part of the book, it mainly described about the prescriptions of invigorating Gi[補氣], which is followed by the prescriptions on enriching blood and nourishing vital essence fluid[補陰血], and the prescriptions on strengthening Gihyeol[補氣血] and tranquilization[安神] are described at the last part of the book. At the current review, the 8 prescriptions of strengthening Gihyeol[補氣血] and tranquilization[安神] of the last part of the book I will be translated, and compared with the similar related comments in the book of "The Famous Prescription Comments on Ancient and Modern Times[古今名醫方論]" to review about the characteristics of formula, prescriptions notes and the relationship of these contents. In terms of formula, the order of prescriptions to strengthen Gihyeol[補氣血] could be listed from the indirectly strengthening prescriptions to the directly strengthening prescriptions. In addition, the list of prescriptions will be sequenced by following the order of weak strengthening prescriptions to the strong strengthening prescriptions. The order of tranquilization prescription must be ordered for the symptoms showing mild psychological symptoms to severe symptoms in terms of severity of symptom, and will be ordered from the prescriptions highly dependent on invigorating Gi[補氣] to the prescriptionless dependent on invigorating Gi[補氣]. In the way of controlling Premier Fire[相火], these prescriptions are ordered from the prescriptions that use indirect methods to the prescriptions that use direct methods Characteristics of the prescription notes could be mentioned that the herbs of invigorating Gi(補氣) is pivotal in strengthening Gihyeol[補氣血] and the sour flavor and pungent flavor acted as negative and positive[陰陽的] when sour flavor and pungent flavor are used to enrich liver, and that sweet flavor could easily indigested to cause abdominal distension. When comparing with the content of "The Famous Prescription Comments on Ancient and Modern Times[古今名醫方論]", it mostly adopted the content as it is, but differentiation of the formula and addition of 2 new prescriptions with their explanation in the middle of the book could be considered to be creative aspect that helped the convenience of readers.