• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.562-568
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• 2014

In this work, synthesis, characterization and antimicrobial activity of series of imidazolines-oxazolines scaffolds 5a-f and 10a-d have been investigated. All the imidazolines-oxazolines derivatives were prepared from acid derivatives 1 and 6a-c, and enantiomerically pure (S)-2-amino-3-methyl-1-butanol in four steps with excellent optical purity. The structures of all newly synthesized compounds have been elucidated by $^1H$, $^{13}C$ NMR, GCMS, and IR spectrometry. Their purity was confirmed using elemental analysis. Some newly synthesized compounds were examined to in-vitro antimicrobial activity. Among the prepared products 10d was found to exhibits the most active against all tested bacteria and fungi with minimal inhibitory concentration (MIC) ranged between 21.9 and $42.6{\mu}g/mL$.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.993-997
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• 2008

Two directional ring-closing metathesis (RCM) was applied successfully to the synthesis of 4'-vinylated carbocyclic nucleoside analogues from the trivinyl intermediate 12, which was readily made using a sequential Claisen rearrangement and ring-closing metathesis (RCM) starting from Weinreb amide 5. An antiviral evaluation of the synthesized compounds against various viruses such as HIV, HSV-1, HSV-2 and HCMV revealed that the guanine analogue 20 have moderate anti-HIV activity in the MT-4 cell line ($EC_{50}$ = 10.2 $\mu$ M).

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.868-869
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• 2006

[ $Cr_2AlC$ ] was synthesized by a reactive hot pressing of $CrC_x(x=0.5)$ and Al powder mixture used as starting materials at the temperature range of $1200^{\circ}C{\sim}1400^{\circ}C$ under 25 MPa in Ar atmosphere. Fully dense $Cr_2AlC$ with high purity was synthesized by hot pressing $CrC_x$ and Al powder mixture at the temperature as low as $1200^{\circ}C$. The average grain size of synthesized bulk $Cr_2AlC$ was varied in the range of $10-100{\mu}m$ depending on hot pressing temperatures. The maximum flexural strength of synthesized bulk $Cr_2AlC$ exceeded 600 MPa.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2626-2630
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• 2009

2'($\beta$)-Hydroxymethylated adenosine is a potent and selective inhibitor of hepatitis C virus (HCV) replication. It targets the RNA-dependent RNA polymerase of HCV, NS5B. Synthesis and antiviral evaluation of carbocyclic versions are described. The cyclopentene intermediate ($9\beta$) was successfully synthesized through sequential Johnson-Claisen orthoester rearrangement and ring-closing metathesis (RCM). Coupling of bases via a Pd(0) catalyst, selective dihydroxylation, and desilylation yielded the target nucleoside analogues. The compounds 17 and 18 were assayed for their ability to inhibit HCV RNA replication in a subgenomic replicon Huh7 cell line and showed moderate antiviral activity with toxicity up to 20.0 and 24.7 ${\mu}g/mL$, respectively.

• Archives of Pharmacal Research
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• v.29 no.11
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• pp.957-962
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• 2006

A novel series of 2-(m-Chlorobenzyl)-4-substituted-1, 1, 3-trioxo-2H, 4H-pyrazolo[4, 5-e][1, 2, 4] thiadiazines (7a-k) were synthesized, and evaluated for their anti-HIV replication in MT-4 cell cultures. Compound (7a) showed activity against HIV-1-induced cytopathicity, with an $EC_{50}$ value of $45.6\;{\mu}M$, but none of the compounds exhibited inhibitory activity against HIV-2.

• YAKHAK HOEJI
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• v.51 no.2
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• pp.103-107
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• 2007

In these study novel 1,4-disubstituted carbocyclic nucleoside analogues were synthesized as potential antiviral agents. The coupling reaction of the alcohol 8${\alpha}$ with natural bases using Mitsunobu reaction afforded the target nucleosides 13, 14. The synthesized compounds were evaluated for their antiviral activity against various viruses such as HIV-1, HSV-1, HSV-2 and HCMV. Cytosine derivative 13 exhibited moderate antiviral activity against HIV-1 (EC$_{50}$=16.4 ${\mu}$M).

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.1
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• pp.1-7
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• 2001

For a parametric uncertain system, there are many results on stability analysis, but only a few synthesis methods. In this paper, we proposed a new target polynomial decision method for the parametric uncertain system to stabilize the closed loop system with maximal parametric $l_2$ stability margin. To this, we used both Lipatov Theorem and coefficient diagram method(CDM). To show the effectiveness of the proposed method, we designed a robust controller for the inverted pendulum system with parametric uncertainties using fixed order pole assignment(FOPA) method and its performance was compared with that of the ${\mu}$ synthesis methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.96-99
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• 2004

The combination of mechano-chemical activation and Self-propagating High-temperature Synthesis (SHS) has widened the possibilities for both methods. For YBCO systems the investigation showed that a short-term mechano-chemical activation of initial powders before SHS leads to single-phase and ultra-fine products. A new technique for preparation ultra-fine high-temperature superconductors of YBCO composition with a grain size d ＜1 ${\mu}{\textrm}{m}$ is developed. The specific feature of the technique is formation of the YBa$_2$Cu$_3$O$_{7-{\delta}}$ crystalline lattice directly from an X-ray amorphous state arising as a result of mechanical activation of the original oxide mixture. The technique allows the stage of formation of any intermediate reaction products to be ruled out. X-ray and magnetic studies of ultra-fine high temperature superconductors (HTS) are carried out. Dimension effects associated with the microstructure peculiarities are revealed. A considerable enhancement of inter-grain critical currents is found to take place in the ultra-fine samples.fine samples.

• Biomolecules & Therapeutics
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• v.20 no.3
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• pp.340-345
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• 2012

Sarsasapogenin (SAR) is a steroidal sapogenin that is used as starting material for the industrial synthesis of steroids. It has various pharmacological benefits, such as antitumor and antidepressant activities. Since its effect on melanin biosynthesis has not been reported, we used murine melanocyte melan-a cells to investigate whether SAR influences melanogenesis. In this study, SAR significantly increased the melanin content of the melan-a cells from 1 to 10 ${\mu}M$. Based on an enzymatic activity assay using melan-a cell lysate, SAR had no effect on tyrosinase and DOPAchrome tautomerase activities. It also did not affect the protein expression of tyrosinase-related protein 1 and DOPAchrome tautomerase. However, protein levels of tyrosinase and microphthalmia-associated transcription factor were strongly stimulated by treatment with SAR. Therefore, our reports suggest that SAR treatment may induce melanogenesis through the stimulation of tyrosinase and microphthalmia-associated transcription factor expression in melan-a cells.

• Bulletin of the Korean Chemical Society
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• v.11 no.2
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• pp.134-139
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• 1990

The hydrogenation catalyst precursors $[(L-L)Rh(NBD)]ClO_4\;(L-L=Fe({\eta}^5-C_5H_4PBu^t\;_2)_2,\;Fe({\eta}^5-C_5H_4PPhBu^t)_2$; NBD = norbornadiene) react with $H_2(1\;atm,\;30^{\circ}C$, MeOH) to yield $[(L-L)HRh({\mu}-H)_3RhH(L-L)]ClO_4$. These hydrido species are fluxional, and variable temperature NMR studies show the existence of a number of equilibria involving both fluxional and non-fluxional species. The synthesis, solution structures, and fluxional behaviors of these hydrides are described.