ELECTRIC FIELD-INDUCED DIRECTOR ORIENTATION OF SMECTIC-A DOMAINS IN AN ISOTROPIC PHASE

Abstract

Electric field-induced director orientation of smeetic-A phase in an isotropic phase has been studied with a polarizing microscope using the binary mixture of octyloxycyanobiphenyl and dodecyl alcohol. Electric field is applied to the samples in which spherical smectic-A domains with and without defects in an isotropic phase are observed. Field-induced orientation of smectic-A director is observed for spherical smectic-A domains with defects but not observed for those without defects below electric field strength of 1.0 V/μm, indicating that the presence of defects facilitates the director orientation. The threshold field for the smectic-A director orientation varies from smectic-A domain to domain, suggesting that the threshold field is dependent on the structure of defects.     

Three-dimensional locally homogeneous Lorentzian affine hyperspheres with constant sectional curvature

We determine 3-dimensional locally homogeneous Lorentzian affine hyperspheres with constant sectional curvature and with zero Pick invariant.     

Size-dependent partitioning of nano/microparticles mediated by membrane lateral heterogeneity

It is important that we understand the physical, chemical, and biological mechanisms that govern the interaction between nanoparticles (NPs) and heterogeneous cellular surfaces because of the possible cytotoxicity of engineered nanomaterials. In this study, we investigated the lateral localization of nano/microparticles within a biomimetic heterogeneous membrane interface using cell-sized two-phase liposomes. We found that lateral heterogeneity in the membrane mediates the partitioning of nano/microparticles in a size-dependent manner: small particles with a diameter of ≤200 nm were localized in an ordered phase, whereas large particles preferred a fluidic disordered phase. This partitioning behavior was verified by temperature-controlled membrane miscibility transition and laser-trapping of associated particles. In terms of the membrane elastic energy, we present a physical model that explains this localization preference of nano/microparticles. The calculated threshold diameter of particles that separates the particle-partitioning phase was 260 nm, which is in close agreement with our observation (200 nm). These findings may lead to a better understanding of the basic mechanisms that underlie the association of nanomaterials within a cell surface.     

Construction of novel quantum-confined structure with lead halide/gemini surfactant hybrids

Novel organic–inorganic hybrid compounds, C₁₆H₄₄N₄Pb₃I₁₀ and C₁₄H₃₄N₂Pb₂I₆, were synthesized by solvent diffusion recrystallization from the dimethylsulfoxide solution containing PbI₂ and gemini ammonium surfactants with different head groups. The results of single crystal X-ray structural analysis showed that the inorganic region of C₁₆H₄₄N₄Pb₃I₁₀ has quasi one-dimensional chains of [Pb₃I₁₀]^4? units, whereas that of C₁₂H₃₀N₂Pb₂I₆ has one-dimensional chains of face-sharing PbI₆ octahedra. The absorption and fluorescence spectra of these compounds also indicate the formation of one-dimensional inorganic chains and quantum-confined structures.     

Modified scattering operator for the Hartree-Fock equation

We study the scattering problem for the Hartree-Fock equation

(HRF)     

Heteroepitaxial film growth of layered compounds with the ZrCuSiAs-type and ThCr2Si2-type structures: From Cu-based semiconductors to Fe-based superconductors

FeAs-based layered superconductors such as F-doped LaFeAsO have recently been investigated intensively because of their high superconducting transition temperatures. Epitaxial films of these compounds are important to examine their intrinsic materials properties as well as to transfer them to device applications. In this review, we first present our research route from transparent p-type oxides semiconductors to the Fe-based superconductors. Then we review growth of epitaxial thin films for the layered oxychalcogenides and oxypnictides. Reactive solid-phase epitaxy technique was inevitable to prepare epitaxial thin films of the oxychalcogenides and Zn-based oxypnictides. On the other hand, epitaxial thin films of Mn-based oxypnictides were grown by standard pulsed laser deposition. These techniques, however, did not grow epitaxial thin films for LaFeAsO. Thus, we developed a modified pulsed laser deposition process and succeeded in obtaining epitaxial thin films of FeAs-based superconductors, LaFeAsO and cobalt-doped SrFe₂As₂.     

Al6Ti2O13, a new phase in the Al2O3–TiO2 system

The compound Al₆Ti₂O₁₃ (hexa­aluminium dititanium trideca­oxide) has been synthesized using an arc‐imaging furnace, which allows fast cooling of melted oxides. The structure consists of infinite double chains of polyhedra running along the c axis. These chains are built up by four kinds of strongly distorted oxygen octa­hedra randomly occupied by either Ti or Al (point symmetry m or m2m), and by trigonal bipyramids exclusively occupied by Al (point symmetry m2m).     

(R)-Eucomic acid, a leaf-opening factor of the model organism, Lotus japonicus

In the post-genomic era, the biological activity of endogenous metabolites can be linked to genomic information via its target protein. Consequently, studies concerned with the identification of endogenous bioactive metabolites from model organisms should be undertaken. (R)-Eucomic acid (1) was identified as an endogenous metabolite concerning leaf movement in the model legume, Lotus japonicus. Absolute stereochemistry was investigated by comparison of physical characteristics of natural and synthetic enantiomers of 1. Identification of endogenous metabolites in a model legume would be particularly advantageous for further studies on the chemical biology of this biologically intriguing phenomenon.     

Copper(I) complexes with fluorinated hydrotris(pyrazolyl)borate: Influence of electronic effects on their structure,physicochemical properties,and reactivity

Copper(I) coordination complexes of the anionic fluorinated ligand, hydrotris(3-trifluoromethyl-5-methyl-1-pyrazolyl)borate (L0f⁻), i.e. the copper(I) carbonyl complex, [Cu^I(L0f)(CO)] (1), the copper(I) triphenylphosphine complex, [Cu^I(L0f)(PPh₃)] (2), the copper(I) acetonitrile complex, [Cu^I(L0f)(NCMe)] (3), and the corresponding copper(I) triphenylphosphine complex with hydrotris(3,5-diisopropyl-1-pyrazolyl)-borate anion (L1⁻), i.e. [Cu^I(L1)(PPh₃)] (4), were synthesized in order to investigate the influence of the electron-withdrawing groups on the pyrazolyl rings. The structures of complexes 1, 2, and 4 were determined by X-ray crystallography. While X-ray crystallography did not show definitive trends in terms of copper(I) atom geometry, the clear influence of the electronic structure of the pyrazolyl rings is observed by spectroscopic techniques, namely, IR and multinuclear NMR spectroscopy. Finally, the relative stability of the copper(I) complexes is discussed.