• BMB Reports
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• v.38 no.2
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• pp.198-205
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• 2005

Resveratrol (RES) and genistein (GEN) are the dietary natural products known to possess chemopreventive property and also the ability to repair DNA damage induced by mutagens/carcinogens. It is believed that the therapeutic activity of these compounds could be primarily due to their interaction with nucleic acids but detailed reports are not available. We here explore the interaction of these drugs with nucleic acids considering DNA and RNA as a potential therapeutic target. The interaction of RES and GEN has been analysed in buffered solution with DNA [saline sodium citrate (SSC)] and RNA [tris ethylene diammine tetra acetic acid (TE)] using UV-absorption and Fourier transform infrared (FTIR) spectroscopy. The UV analysis revealed lesser binding affinity with nucleic acids at lower concentration of RES (P/D = 5.00 and 10.00), while at higher drug concentration (P/D = 0.75, 1.00 and 2.50) hyperchromic effect with shift in the ${\lambda}_{max}$ is noted for DNA and RNA. A major RES-nucleic acids complexes was observed through base pairs and phosphate backbone groups with K = $35.782\;M^{-1}$ and K = $34.25\;M^{-1}$ for DNA-RES and RNA-RES complexes respectively. At various concentrations of GEN (P/D = 0.25, 0.50, 0.75, 1.00 and 2.50) hyperchromicity with shift in the ${\lambda}_{max}$ from 260 $\rightarrow$ 263 om and 260 $\rightarrow$ 270 nm is observed for DNA-GEN and RNA-GEN complexes respectively. The binding constant (from UV analysis) for GEN-nucleic acids complexes could not be obtained due to GEN absorbance overlap with that of nucleic acids at 260 nm. Nevertheless a detailed analysis with regard to the interaction of these drugs (RES/GEN) with DNA and RNA could feasibly be understood by FTIR spectroscopy. The NH band of free DNA and RNA which appeared at $3550-3100\;cm^{-1}$ and $3650-2700\;cm^{-1}$ shifted to $3450-2950\;cm^{-1}$ and $3550-3000\;cm^{-1}$ in DNA-RES and RNA-RES complexes respectively. Similarly shifts corresponding to $3650-3100\;cm^{-1}$ and $3420-3000\;cm^{-1}$ have been observed in DNA-GEN and RNA-GEN complexes respectively. The observed reduction in NH band of free nucleic acids upon complexation of these drugs is an indication of the involvement of the hydroxyl (OH) and imino (NH) group during the interaction of the drugs and nucleic acids (DNA/RNA) through H-bonded formation. The interaction of RES and GEN with bases appears in the order of G $\geq$ T > C > A and A > C $\geq$ T > G. Further interaction of these natural compounds with DNA and RNA is also supported by changes in the vibrational frequency (shift/intensity) in symmetrical and asymmetrical stretching of aromatic rings of drugs in the complex spectra. No appreciable shift is observed in the DNA and RNA marker bands, indicating that the B-DNA form and A-family conformation of RNA are not altered during their interaction with RES and GEN.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.314-314
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• 2016

In this paper, the effects of carrier concentration on dielectric constant of ITO films were investigated by spectroscopic ellipsometry. From SE results, we find the pronounced shift of the ${\varepsilon}1$ peaks toward high energy with concentration; while contrarily, the ${\varepsilon}2$ values at low energy region increases with decreasing concentration. These shifts are attributed to the Burstein-Moss and free-carrier absorption effects within ITO films. With increases carrier concentration, the values of extinction coefficients show quite different behaviors in range of wavelength from 200 to 1200 nm. The reduction in k at ${\lambda}{\leq}500nm$, while increasing at ${\lambda}{\geq}500nm$ was observed. The QE of HJ solar cells behaviors can be roughly classified into two regions: short-wavelengths (${\leq}650nm$) and long-wavelengths region (${\geq}650nm$). With increasing carrier concentration as well as energy band gap, QE shows improvement at short-wavelength, while at long-wavelength QE shows opposite trend. Widening band gap energy due to Burstein-Moss shift is the key to improve QE in short-wavelength; simultaneously FCA effect due to optical scattering is attributed to the reduction in QE at long-wavelength. In spite of band gap extension, Jsc calculated from QE decreases from 34.7 mA/cm2 to 33.2 mA/cm2 with increasing carrier concentration. It demonstrated that FCA effect may more govern Jsc in the HJ solar cells.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.3
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• pp.111-119
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• 2014

A novel pulsed laser ablation process in liquid was investigated to prepare scheelite-type ceramic [calcium tungstate ($CaWO_4$) and calcium molybdate ($CaMoO_4$)] nanocolloidal particles. The crystalline phase, particle morphology, particle size distribution, absorbance and optical band-gap were investigated. Stable colloidal suspensions consisting of well-dispersed $CaWO_4$ and $CaMoO_4$ nanoparticles with narrow size distribution could be obtained without any surfactant. Particle tracking analysis using optical microscope combined with image analysis was applied for a fast determination of particle size distribution in the prepared nanocolloidal suspensions. The mean nanoparticle size of $CaWO_4$ and $CaMoO_4$ colloidal nanoparticles were 16 nm and 30 nm, with the standard deviations of 2.1 and 5.2 nm, respectively. The optical absorption edges showed blue-shifted values about 60~70 nm than those of reported in bulk crystals. And also, the estimated optical energy band-gaps of $CaWO_4$ and $CaMoO_4$ colloidal particles were 5.2 and 4.7 eV. The observed band-gap widening and blue-shift of the optical absorbance could be ascribed to the quantum confinement effect due to the very small size of the $CaWO_4$ and $CaMoO_4$ nanocolloidal particles prepared by pulsed laser ablation in liquid.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1825-1831
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• 2006

The influence of solvent viscosity on conformational dynamics of the heme-pocket, a small vacant site near the binding site of myoglobin (Mb) and hemoglobin (Hb), and playing a functionally important role by serving as a station in ligand binding and escape, was studied by probing time-resolved vibrational spectra of CO photodissociated from MbCO and HbCO in $D_2O$, 75 wt% glycerol/$D_2O$, and trehalose at 283 K. Two absorption bands ($B_1$ and $B_2$) of the sample in viscous solvents, arising from CO in the heme pocket, are very similar to those in $D_2O$. Two bands in Mb and Hb under all three solvents exhibit very similar nonexponential spectral evolution ($B_1$ band; blue shifting and broadening, $B_2$ band; narrowing with a negligible shifting), suggesting that in the present experimental time window of 100 ps, the extents of the spectral shift and narrowing is much influenced neither by the viscosity of solvent nor by the quaternary contact of Hb. Spectral evolution can be described by a biexponential function with a fast universal time constant of 0.52 ps and a slow time constant ranging from 13 to 32 ps. For both proteins in all three solvents majority of spectral evolution occurs with the fast universal time constant. The magnitude of the slow rate in the spectral shift of B1 band decreases with increasing solvent viscosity, indicating that it is influenced by global conformational change which is retarded in viscous solvent, thereby serve as a reporter of global conformational change of heme proteins after deligation.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1973-1976
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• 2008

Electronic photodepletion spectrum of dibenzo-18-crown-6 with a potassium ion ($K^+$-DB18C6) was obtained in the gas phase using electrospray ionization and quadrupole ion-trap reflectron time-of-flight mass spectrometry. The spectrum exhibited rather a broad absorption band at 36350 $cm^{-1}$, which was tentatively assigned as the origin of the S1 band. The photodepletion spectrum of $Cs^+$-DB18C6 was also obtained to elaborate the effects of metal cations on electronic and geometric structures of metal cation-DB18C6 complexes. We found that the S1 band of $Cs^+$-DB18C6 was red-shifted by 180 $cm^{-1}$ from that of $K^+$-DB18C6. With the results of quantum theoretical calculations using the density functional theory, we suggested that the red-shift arose mainly from weaker binding of $Cs^+$ to DB18C6 than that of K+, which resulted from a larger size of $Cs^+$ than that of the cavity in DB18C6.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.52-60
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• 1999

Fabricability of phase shifted grating filters has been theoretically studied by an effective index transfer matrix method. In the optical band-pass filter with multiple ${\lambda}/4$ phase-shifts, the phase-shift error and random variation of the grating period should be suppressed such that corresponding resonance frequency lies within, the filter pass-band. The tolerance for the relative error is less than $10^3$, and is quite stringent in typical filters for WDM application. End facet reflection produces ripple in the transmission spectra and the reflectivity should be less than 1% in order to keep the ripple less than 0.25dB. Also, the effect of waveguide absorption loss is enhanced by the resonance in the filter, and the absorption should be limited to 1dB/cm for the signal loss of less than 0.2dB.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.3
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• pp.122-126
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• 2003

In this study, $Zn_{0.86}Mn_{0.14}$Te epilayer of 0.7 $\mu\textrm{m}$-thickness was grown on GaAs(100) substrate by using hot wallepitaxy. GaAs(100) substrate was removed from $Zn_{0.86}Mn_{0.14}$Teepilayer by the selective etching solution. The crystal structure and the lattice constant of only Z $n_{0.86}$ M $n_{0.14}$Te epilayer were investigated to be zincblende and 6.140 $\AA$ from X-ray diffraction pattern, respectively. Mn composition x of $Zn_{1-x}Mn_x$Te epilayer was found to be 0.14 using this lattice constant and Vegard's law. The crystal quality of the epilayer was confirmed to be very good due to 256 arcsec-full-width at half-maximum of the double crystal rocking curve. The absorption spectra from the transmission ones were obtained to measure the band gap energy of $Zn_{0.86}Mn_{0.14}$Te epilayer from 300 K to 10 K. With the decreasing temperature,. strong absorption regions in the absorption spectra were shifted to higher energy side and the absorption peak meaning the free exciton formation appeared near the absorption edge. The band gap energy values of $Zn_{0.86}Mn_{0.14}$Te epilayer at 0 K and 300 K were found to be almost 2.4947 eV and 2.330 eV from the temperature dependence of the free exciton peak position energy of $Zn_{0.86}Mn_{0.14}$Te epilayer, respectively. The free exciton peak position energy of $Zn_{0.86}Mn_{0.14}$Te epilayer without GaAs substrate was larger 15.4 meV than photoluminescence peak position energy at 10 K. This energy difference between two peaks was analysed to be Stokes shift.

• Bulletin of the Korean Chemical Society
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• v.24 no.10
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• pp.1465-1469
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• 2003

A neutral ligand is synthesized and studied for the binding properties with anions by electrochemical methods. The binding of 1,8-bis[(N'-phenylureido)ethyloxy]anthraquinone (BPUA) with $H_2PO_4^-$ makes cathodic shift of its electrochemical potentials and red shift of absorption band. This novel neutral anion receptor BPUA binds anions through hydrogen bonding and show high selectivity with $H_2PO_4^-$ over $CH_3CO_2^-,CI^-,{\;}and{\;}HSO_4^-$. The selecivity of H_2PO_4^-$ over $CH_3CO_2^-,CI^-,{\;}and{\;}HSO_4^-$ may be attributed to the stronger hydrogen bonding with urea moiety and also with anthraquinone moiety of BPUA receptor, and also the higher complementarity of the cavity of BPUA for tetrahedral H_2PO_4^-$.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.843-846
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• 1992

This thesis was investigated on optical-and ion-induced characteristics in positive(a-$Se_{75}Ge_{25}$) and negative (Ag/a-$Se_{75}Ge_{25}$) resists for focused-ion-beam microlithogaphy. The a-$Se_{75}Ge_{25}$ inorganic thin film shows an increase in optical absorption after exposure to$\sim$$10^{16}$ dose(ions/$cm^{2}$) of Ga ions. The observed shift in the absorption edge toward longer wavelengths is consistent with that in films exposed to band-gap photons ($\sim$$10^{20}$ photons/$cm^{2}$). But, ion induced shift is twice as much as that in film exposed to optical radiation. This result may be related with microstructural rearrangements with in the short range of SeGe network. Due to changes in the short range order, the chemical bonding may be affected, which results in increased chemical dissolution in ion-induced film. Also, this resist exhibits good thermal stability because of its high Tg(~220$^{\circ}C$). The composition of deposited film measured by AES is consistent with that of bulk.

• Advances in nano research
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• v.2 no.2
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• pp.111-119
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• 2014

The chemical synthesis of anisotropic defective polyaniline/Ag composite (PANI/Ag) is explored using silver nitrate ($AgNO_3$) as the precursor material. This study provides a simple method for the formation of PANI/Ag nanocomposites at two different aniline concentrations $5{\mu}l$ (PANC5) and $10{\mu}l$ (PANC10). The composite PANC5 exhibits UV-Visible absorption peaks at 436 nm and 670 nm whereas, PANC10 exhibits absorption peaks at 446 nm and 697 nm. This shift is caused by the strong interaction between polyaniline and silver. The characterized FTIR peaks observed at around $3410cm^{-1}$ (PANC5) and $3420cm^{-1}$ (PANC10) was due to the N-H stretching vibrations. The appearance of a broad band instead of a sharp peak can be attributed due to the presence of a high concentration of N-H groups in the nanocomposite. The TEM images show that the sample contains defective spherical, truncated triangular and rod shaped particles. The results showed that the PANI/Ag nanocomposites are composed of nano-sized particles of 43-53 nm that contain Ag domains of 33-37 nm with polymer thickness 5.7-11.2 nm at two different aniline concentrations.