Enhancement of Planar Orientation of Reactive Mesogen Molecules for Optical Retarder Film by Anisotropic Surface Plasma Treatment

We proposed a method for enhancing the planar orientation of reactive mesogen (RM) molecules by means of anisotropic plasma treatment. Anisotropic surface plasma, of which energy density is dependent on the azimuthal angle, was generated by column-shaped ceramic electrodes. The anisotropic plasma was discharged on the surface of a polyvinyl alcohol (PVA) alignment layer before the rubbing process began. The contact angle of the surface was increased from 12° to 83° after plasma treatment, indicating a hydrophobic property of the surface. From the atomic force microscopy (AFM) measurement, it was found that the grain size of the PVA layer was reduced and that the grooved patterns were formed provided that the plasma direction was parallel to the rubbing direction of the surface. Consequently, the planar orientation was enhanced, and the in-plane retardation of the photo-polymerized RM films increased when the parallel plasma was treated on the surface.

Planar polarization of cilia in the zebrafish floor-plate involves Par3-mediated posterior localization of highly motile basal bodies

ABSTRACTTo produce a directional flow, ciliated epithelia display a uniform orientation of ciliary beating. Oriented beating requires planar cell polarity (PCP), which leads to planar orientation and asymmetric positioning of the ciliary basal body (BB) along the polarity axis. We took advantage of the polarized mono-ciliated epithelium of the embryonic zebrafish floor plate to investigate by live-imaging the dynamics and mechanisms of BB polarization. We showed that BBs, although bearing a cilium, were highly motile along the antero-posterior axis. BBs contacted both the anterior and the posterior membranes, with a bias towards posterior contacts from early somitogenesis on. Contacts exclusively occurred at junctional Par3 local enrichments or “patches” and were often preceded by transient membrane digitations extending towards the BB, suggesting focused cortical pulling forces. Accordingly, BBs and Par3 patches were linked by dynamic microtubules. We showed that Par3 became posteriorly enriched prior to BB posterior positioning and that floor plate polarization was impaired upon Par3 patches disruption triggered by Par3 or aPKC overexpression. In the PCP mutant Vangl2, where floor plate cells fail to polarize, we observed that BB were still motile but presented behavioral defects, such as ectopic contacts with lateral membranes that correlated with Par3 patch fragmentation and spreading to lateral membranes. Our data lead us to propose an unexpected function for posterior local Par3 enrichment in controlling BB asymmetric positioning downstream of the PCP pathway via a microtubule capture/shrinkage mechanism.

Pure and mixed ordered monolayers of tetracyano-2,6-naphthoquinodimethane and hexathiapentacene on the Ag(100) surface

We report on mixed ordered monolayers of the electron acceptor-type molecule tetracyano-2,6-naphthoquinodimethane (TNAP) and the electron donor-type molecule hexathiapentacene (HTPEN). This investigation was motivated by the general question which type of mixed stoichiometric structures are formed on a surface by molecules that are otherwise typically used for the synthesis of bulk charge-transfer materials. The layers were obtained by vacuum deposition on the Ag(100) surface and analyzed by low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The formation of the mixed structure occurs spontaneously. An important motif for the structure formation is given by hydrogen bonds between the TNAP molecules. Both molecules, TNAP and HTPEN also form well-ordered monolayers on the Ag(100) surface on their own. In all structures, the molecules are adsorbed in a planar orientation on the surface. We discuss the influence of intermolecular charge transfer on the ordering in the mixed structure.