Scientific Commons: W. S. Choi

Localized electronic states induced by defects and possible origin of ferroelectricity in strontium titanate thin films (2008)

Kim, Yong Su, Kim, J., Moon, S. J., Choi, W. S., Chang, Y. J., ...

Several defect configurations including oxygen vacancies have been investigated as possible origins of the reported room-temperature ferroelectricity of strontium titanate (STO) thin films [Appl....

Bandwidth-Controlled Insulator-Metal Transition and Correlated Metallic State in 5$d$ Transition Metal Oxides Sr$_{n+1}$Ir$_{n}$O$_{3n+1}$ ($n$=1, 2, and $\infty$) (2008)

Moon, S. J., Jin, H., Kim, K. W., Choi, W. S., Lee, Y. S., Yu, J., ...

We investigated the electronic structures of the 5$d$ Ruddlesden-Popper series Sr$_{n+1}$Ir$_{n}$O$_{3n+1}$ ($n$=1, 2, and $\infty$) using optical spectroscopy and first-principles calculations. As...

Optical study of the free-carrier response of LaTiO₃/SrTiO₃ superlattices (2008)

Seo, S. S. A., Choi, W. S., Lee, H. N., Yu, Li, Kim, Kyungwan W., Bernhard, Christian, ...

We used infrared spectroscopic ellipsometry to investigate the electronic properties of LaTiO₃/SrTiO₃ superlattices (SLs). Our results indicated that, independent of the SL periodicity and...

Optical study of the free-carrier response of LaTiO₃/SrTiO₃ superlattices (2008)

Seo, S. S. A., Choi, W. S., Lee, H. N., Yu, Li, Kim, Kyungwan W., Bernhard, Christian, ...

We used infrared spectroscopic ellipsometry to investigate the electronic properties of LaTiO₃/SrTiO₃ superlattices (SLs). Our results indicated that, independent of the SL periodicity and...

Composition-dependent polarization switching behaviors of (111)-preferred polycrystalline Pb(Zr_{x}Ti_{1-x})O_{3} thin films (2007)

Jo, J. Y., Yang, S. M., Han, H. S., Kim, D. J., Choi, W. S., Noh, T. W., ...

We investigated the time-dependent polarization switching behaviors of (111)-preferred polycrystalline Pb(ZrxTi1-x)O3 thin films with various Zr concentrations. We could explain all the polarization...

Electronic structures of hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films (2007)

Choi, W. S., Kim, D. G., Seo, S. S. A., Moon, S. J., Lee, D., Lee, J. H., ...

We investigated the electronic structure of multiferroic hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films using both optical spectroscopy and first-principles calculations. Using artificially...

Orbital-Driven Electronic Structure Changes and the Resulting Optical Anisotropy of the Quasi-Two-Dimensional Spin Gap Compound La4Ru2O10 (2007)

Moon, S. J., Choi, W. S., Kim, S. J., Lee, Y. S., Khalifah, P. G., Mandrus, D., ...

We investigated the electronic response of the quasi-two-dimensional spin gap compound La4Ru2O10 using optical spectroscopy. We observed drastic changes in the optical spectra as the temperature...

Optical Study of the Free Carrier Response of LaTiO3/SrTiO3 Superlattices (2007)

Seo, S. S. A., Choi, W. S., Lee, H. N., Yu, L., Kim, K. W., Bernhard, C., ...

We used infrared spectroscopic ellipsometry to investigate the electronic properties of LaTiO3/SrTiO3 superlattices (SLs). Our results indicated that, independent of the SL periodicity and individual...

Thermomechanical properties of AlN-Cu composite materials prepared by solid state processing (2007)

Lee, K.M., Oh, D.K., Choi, W.S., Weißgärber, T., Kieback, B.

Dielectric constants of Ir, Ru, Pt, and IrO2: Contributions from bound charges (2006)

Choi, W. S., Seo, S. S. A., Kim, K. W., Noh, T. W., Kim, M. Y., Shin, S.

We investigated the dielectric functions $\epsilon$($\omega$) of Ir, Ru, Pt, and IrO$_2$, which are commonly used as electrodes in ferroelectric thin film applications. In particular, we investigated...

Effects of natural sequence variation on recognition by monoclonal antibodies neutralize simian immunodeficiency virus infectivity.

Choi, W S, Collignon, C, Thiriart, C, Burns, D P, Stott, E J, Kent, K A, ...

The determinants of immune recognition by five monoclonal antibodies (KK5, KK9, KK17, Senv7.1, and Senv101.1) that neutralize simian immunodeficiency virus infectivity were analyzed. These five...

Encapsidation of genetically engineered poliovirus minireplicons which express human immunodeficiency virus type 1 Gag and Pol proteins upon infection.

Porter, D C, Ansardi, D C, Choi, W S, Morrow, C D

The use of recombinant viruses for the expression of a wide array of foreign proteins has become commonplace during the last few years. Recently, we have described the construction and...

Expression of human immunodeficiency virus type 1 (HIV-1) gag, pol, and env proteins from chimeric HIV-1-poliovirus minireplicons.

Choi, W S, Pal-Ghosh, R, Morrow, C D

Recent studies have demonstrated that genomes of poliovirus with deletions in the P1 (capsid) region contain the necessary viral information for RNA replication. To test the effects of the...

Evidence that brain prostaglandin E2 is involved in physiological sleep-wake regulation in rats.

Matsumura, H, Honda, K, Choi, W S, Inoué, S, Sakai, T, Hayaishi, O

We reported in previous studies that prostaglandin E2 (PGE2) has central effects of augmenting wakefulness and suppressing slow-wave sleep (SWS) and paradoxical sleep (PS) in rats. In the present...