Management of Fetal Growth Arrest in One of Dichorionic Twins: Three Cases and a Literature Review

Progressive fetal growth restriction (FGR) is often an indication for delivery. In dichorionic diamniotic (DD) twin pregnancy with growth restriction only affecting one fetus (selective fetal growth restriction: sFGR), the normal twin is also delivered prematurely. There is still not enough evidence about the optimal timing of delivery for DD twins with sFGR in relation to discordance and gestational age. We report three sets of DD twins with sFGR (almost complete growth arrest affecting one fetus for ≥2 weeks) before 30 weeks of gestation. The interval from growth arrest to delivery was 21–24 days and the discordance was 33.7–49.8%. A large-scale study showed no difference of overall mortality or the long-term outcome between immediate and delayed delivery for FGR, while many studies have identified a risk of developmental delay following delivery of the normal growth fetus before 32 weeks. Therefore, delivery of DD twins with sFGR should be delayed if the condition of the sFGR fetus permits in order to increase the gestational age of the normal growth fetus

Broken-Symmetry Ground States of Halogen-Bridged Binuclear Metal Complexes

Based on a symmetry argument, we study ground states of what we call MMX-chain compounds, which are the new class of halogen-bridged metal complexes. Commensurate density-wave solutions of a relevant multi-band Peierls-Hubbard model are systematically revealed within the Hartree-Fock approximation. We numerically draw ground-state phase diagrams, where various novel density-wave states appear.Comment: 5 pages, 4 figures embedded, to appear in Phys. Lett.

Orientation and film thickness dependencies of (100)- and (111)-oriented epitaxial Pb(Mg1/3Nb2/3)O3 films grown by metal organic chemical vapor deposition

Abstract(100)- and (111)-oriented epitaxial Pb(Mg1/3Nb2/3)O3 films with 500 and 1300 nm in thickness were grown by metal organic chemical vapor deposition. Remained strain was almost relaxed because the crystal structure of the films was almost the same as that of bulk Pb(Mg1/3Nb2/3)O3. Relative dielectric constant showed the maximum value against the temperature that depended on the measurement frequency. Maximum relative dielectric constant, εr(max.), and the temperature showing εr(max.), T(max.), decreased and increased with the frequency, respectively, are in good agreement with reported data for the bulk. εr(max.) and T(max.), respectively increased and decreased with the film thickness and (111)-oriented films showed larger value than that of the (100)-oriented one. Ferroelectricity was observed for all films up to 297 K and monotonously decreased with increasing temperature. Saturation polarization value increased with the film thickness and (111)-oriented films showed larger value than (100)-oriented ones. On the other hand, the coercive field decreased with increasing film thickness, but was almost independent with the film orientation