• YAKHAK HOEJI
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• v.53 no.4
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• pp.228-234
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• 2009

Topoisomerase I (Topo I) participates in the DNA replication, transcription, and repair. Binding of Topo I inhibitor to the Topo I-DNA cleavage complex forms stabilized ternary complex which blocks DNA religation and ultimately causes cell death. Camptothecin (CPT) and its derivatives have been among the most effective anticancer drugs by inhibition of topo I. However, efforts to synthesize non-CPT drugs have been actively going on because the CPT derivatives have several limitations such as poor solubility, short half-life, and side effects. As an indenoisoquinoline, NSC314622 is not as potent as CPT, but its chemical stability and slower reversibility of the cleavage complex made it a good lead compound. Recently, a series of indenoisoquinoline analogues were synthesized with substituted dimethoxy or methylenedioxy on the aromatic ring and alkylamino on the lactam nitrogen. Some of them showed quite good Topo I inhibitory activity. Using the computer docking program, Surflex-Dock, indenoisoquinoline analogues were docked into the human Topo I-DNA cleavable complex. The docking results showed that the compounds with activity better than NSC314622 intercalated between the -1 and +1 base pairs at the cleavage site, but those with little or no activities did not appear to intercalate. These results could be useful to design new Topo I inhibitors improved than CPT.

• Journal of Photoscience
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• v.9 no.2
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• pp.376-378
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• 2002

Role of cl$^{[-10]}$ in photosynthetic oxygen-evolving complex was studied by light-induced Fourier transform infrared (FTIR) spectroscopy. cl$^{[-10]}$ depletion resulted in the suppression of amide I and amide II IR modes upon S$_1$ to S$_2$ transition. Br$^{[-10]}$ , 1$^{[-10]}$ and N0$_3$$^{[-10]}$ substituted FTIR difference spectra were very similar to that in cl$^{[-10]}$ reconstitution. F$^{[-10]}$ and $CH_3$COO$^{[-10]}$ substituted spectra were largely distorted. We succeeded in detecting the structural change of N0$_3$ $^{[-10]}$ in the cl$^{[-10]}$ site upon the S$_1$ to S$_2$ transition from $^{14}$ N0$_3$$^{[-10]}$ /$^{15}$ N0$_3$$^{[-10]}$ difference spectrum.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.301-303
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• 2001

In this paper we present a Capacitor Charging Power Supply (CCPS) using a series-resonant three-level inverter topology to improve voltage regulation and use semiconductor switches having low blocking voltage capability such as MOSFETs. This inverter can be operated with two modes, Full Power Mode (FPM) and Half Power Mode (HPM). In FPM inverter supplies the high frequency step up transformer with full DC-link voltage and in HPM with half DC-link voltage. HPM switching method will be adopted when CCPS output voltage reaches the preset target value and operates in refresh mode-charge is maintained on the capacitor. In this topology each semiconductor devices blocks a half of the DC-link voltage[2]. A 15kW, 30kV CCPS has been built and will be tested for an electric precipitator application. The CCPS operates from an input voltage of 500VDC and has a variable output voltage between 10 to 30kV and 1kHz repetition rate at 44nF capacitive load [3]. A resonant frequency of 67.9kHz was selected and a voltage regulation of $0.83\%$ has been achieved through the use of half power mode without using the forced cut off the switch current [1]. The theory of operation, circuit topology and test results are given.

• Journal of the Korean Ceramic Society
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• v.42 no.7 s.278
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• pp.449-454
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• 2005

A waveguide method is developed to study the materials with relatively large dielectric constants at microwave range. Basically, the method is similar to the previous waveguide methods represented by short-circuit line and transmission/reflection measurement methods. However, the complex permittivity is not determined by the shift in resonance frequencies, but by numerical analysis of measured scattering parameters. In order to enhance microwave penetration into the specimen with relatively large permittivity, a dielectric plate with lower permittivity is employed for impedance matching. The influences of air gap between the specimen and waveguide wall are evaluated, and the corresponding errors are estimated. The propagation of higher order modes is also considered. Experimental results for several reference ceramics are presented.

• Transactions of Materials Processing
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• v.8 no.5
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• pp.507-519
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• 1999

An approach using the energy method has veen proposed for the analysis of cone spinning having the complicated deformation modes mixed by shear and normal deformation. In the proposed method, the corresponding solution is found through optimization of the total energy dissipation with respect to the parameters assumed by the velocity field defined as the variation of the length in longitudinal direction. The sheet blank is divided into three layers to consider the bending effect and the energy dissipated by shear deformation is superposed to the energy consumption due to normal deformation related with the shrinking deformation is superposed to the energy consumption due to normal deformation related with the shrinking deformation of axi-symmetric sheet element for the evaluation of total deformation energy. In order to check the validity of the proposed method, the complex spinning for making the conical cup is analyzed and the computed results are compared with the experimental results. In comparison of the computed results with existing experimental results,, the good agreement is obtained for the variation of outer radius and the distribution of thickness, and it has thus been shown that the present approach is applicable to the analysis of complex spinning.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3385-3390
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• 2010

$Li^+$ ion complex of azacrown ether with restricted motion of freedom and pseudo-bilateral symmetry was studied by infrared spectroscopy, which has shown simplified and broadened vibrational features. The C=O and N-H stretching bands, in particular, shows anomalous broadening nearly ${\sim}50\;cm^{-1}$. The density functional calculation at the level of BP86/6-31+$G^{**}$ shows that $Li^+$ ion is trapped and rather free to move around inside the cavity, as much as about $0.70\;{\AA}$. Through the relocation of $Li^+$ ion inside the cavity, the conformational changes would occur rapidly in its symmetry $C_1\;{\rightleftarrows}\;C_2\;{\rightleftarrows}\;C_1$$. The potential barrier was obtained to be merely ~2.2 kJ/mol for $C_1\;{\rightarrow}\;C_2$. During this conformational alteration, the amide backbone twists concurrently its dihedral angle side to side about up to ${\pm}3$ degree. Selected vibrational modes were interpreted in terms of the force constant variations of local symmetry coordinates between conformations in the framework of $C_1\;{\rightleftarrows}\;C_2\;{\rightleftarrows}\;C_1$.

• Bulletin of the Korean Chemical Society
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• v.23 no.6
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• pp.851-856
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• 2002

The Reaction of S-methyl-S-cysteine(L-Smc) with racemic $s-cis-[Co(demba)Cl_2]-1$ (Hydmedba = $NN'-dimethylethylenediamine-NN'-di-\alpha-butyric$, acid) yields ${\Delta}$-s-cis-[Co(dmedba)(L-Smc)] 2 with N, O-chelation. Oxidation of sulfur of 2 with $H_2O_2$ in a 1 : 1 mole ratio gives ${\Delta}$-s-cis[Co(dmedba)(L-S(O)mc)] 3 having an uncoordinated sulfenate group. Oxidation of sulfur of L-Sm with $H_2O_2in$ a 1: 1 mole ratio produces S-methyl-L-cysteinesulfenate (L-S(O)me) 5. Direct reaction of 1 with 5 in basic medium gives an N.O-chelated ${\Delta}$s-cis[Co(dmedba)(L-S(O)mc)-N.O], which turmed out be same as obtained by oxidation of 2, while an N, S-chelated ${\Delta}$-s-cis-[Co(dmedba)(S-S(O)mc)-N,O] complex 4 is obtained in acidic medium from the reaction of 1 with 5. This is one of the rare $[$Co^{III}$(N_2O_2-type$ ligand)(amino acid)] type complex preparations, where the reaction conditions determine which mode of N, O and N, S caelation modes is favored.

• Tribology and Lubricants
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• v.39 no.6
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• pp.221-227
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• 2023

A rotordynamic system consists of components that undergo rotational motion. These components include shafts, impellers, thrust collars, and components that support rotation, such as bearings and seals. The motion of this type of rotating system can be modeled as two-dimensional motion and, accordingly, the equation of motion for the rotordynamic system can be represented using complex coordinates. The directional frequency response function (dFRF) can be derived from this complex coordinate system and used as an effective analytical tool for rotating machinery. However, the dFRF is not widely used in the field because most previous studies and commercial software are based on real coordinate systems. The objective of the current study is to introduce the dFRF and show that it can be an effective tool in rotordynamic analysis. In this study, the normal frequency response function (nFRF) and dFRF are compared under rotordynamic analysis for isotropic and unisotropic rotors. Results show that in the nFRF, the magnitude of the response is the same for both positive and negative frequencies, and the response is similar under all modes. Consequently, the severity of the mode cannot be identified. However, in the dFRF, the forward and backward modes are clearly distinguishable in the frequency domain of the isotropic rotor, and the severity of the mode can be identified for the unisotropic rotor.

• Journal of Domestic Journal Test
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• v.11 no.2
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• pp.221-227
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• 2023

− A rotordynamic system consists of components that undergo rotational motion. These components include shafts, impellers, thrust collars, and components that support rotation, such as bearings and seals. The motion of this type of rotating system can be modeled as two-dimensional motion and, accordingly, the equa- tion of motion for the rotordynamic system can be represented using complex coordinates. The directional fre- quency response function (dFRF) can be derived from this complex coordinate system and used as an effective analytical tool for rotating machinery. However, the dFRF is not widely used in the field because most pre- vious studies and commercial software are based on real coordinate systems. The objective of the current study is to introduce the dFRF and show that it can be an effective tool in rotordynamic analysis. In this study, the normal frequency response function (nFRF) and dFRF are compared under rotordynamic analysis for isotropic and unisotropic rotors. Results show that in the nFRF, the magnitude of the response is the same for both pos- itive and negative frequencies, and the response is similar under all modes. Consequently, the severity of the mode cannot be identified. However, in the dFRF, the forward and backward modes are clearly distinguishable in the frequency domain of the isotropic rotor, and the severity of the mode can be identified for the uniso- tropic rotor.

• Archives of Pharmacal Research
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• v.25 no.6
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• pp.807-816
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• 2002

Dihydrofolate reductases (DHFR) of human, Candida albicans and E. coli were docked with their original ligands of X-ray crystal complex using QXP (Quick eXPlore), a docking program. Conditions to reproduce the crystal structures within the root mean square deviation (rmsd) of 2.00 $\AA$ were established. Applying these conditions, binding modes and species-specificities of a novel antibacterial compound, $N^4-(2-acetoxyethoxymethyl)-2-acetylpyridine$ thiosemicarbazone (MTSC), were studied. As the results, the docking program reproduced the crystal structures with average rmsd of six ligands as 0.91 $\AA$ ranging from 0.49 to 1.45 $\AA$. The interactions including the numbers of hydrogen bonds and hydrophobic interactions were the same as the crystal structures and superposition of the crystal and docked structures almost coincided with each other. For AATSC, the results demonstrated that it could bind to either the substrate or coenzyme sites of DHFR in all three species with different degrees of affinity. It confirms the experimentally determined kinetic behavior of uncompetitive inhibition against either the inhibitor or the coenzyme. The docked MTSC overlapped well with the original ligands and major interactions were consistent with the ones in the crystal complexes. The information generated from this work should be useful for future development of antibacterial and antifungal agents.