Coulomb interactions and optically-active vibrations of Ionic crystals—I: Theory and application to NaNO3

A method is given for polarizable-ion model calculations of optically-active vibration frequencies of ionic crystals together with an illustrative application. Frequency splittings originating from Coulomb interactions between induced dipoles are explained satisfactorily by the calculations. Important discrepancies remaining in rigid-ion treatments are considerably reduced by taking into account the electronic polarizabilities. Some effects of anisotropy of the ionic polarizabilities on crystal vibrations are discussed briefly.     

Lattice dynamics of wurtzite-type crystals—II

We evaluated, in the preceding paper, the effective ionic charge and electronic polarizability for wurtzite-type crystals on the basis of the polarizable-ion model given by Born and Huang. With use of the quantities so evaluated, we here estimated the short-range force constants from observed frequencies, elastic constants, and piezoelectric constants after simplifying Born and Huang's procedures. The resulting set of force constants can reproduce the observed data except for the piezoelectric constants. This poor reproduction of the piezoelectric constants is due to the fact that the long-range force is emphasized in the polarizable-ion model.     

Liposomes possess drastic capabilities for topological transformation

Morphological and topological changes of biological membranes play essential roles in cellular activities. It has been thought that these transformations are made possible through interactions with proteins. However, direct observation of giant liposomes by optical dark-field microscopy reveals that the lipid bilayer itself possesses the ability to undergo topological transformation.     

Superior Nanoporous Polyimides via Supercritical CO2 Drying of Jungle‐Gym‐Type Polyimide Gels

We report novel nanoporous polyimides formed from jungle‐gym‐type rigid polyimide gels by supercritical CO₂ drying. By virtue of supercritical CO₂ drying to avoid the collapse of nanostructure, porosity above 90 vol.‐% was achieved. We found a rich variety of nanoporous structures in the range of 50–800 nm such as crisp fragments, minute network, and highly‐connected beads. These characteristic structures were formed by the competitive progress of liquid‐liquid phase separation and crystallization induced due to the two chemical reactions of end‐crosslinking and thermal imidization during gelation.

     

N‐Methyl‐N‐[(Z)‐2‐phenyl­propenyl]­thio­benz­amide

The crystal structure of the title thio­benz­amide, C₁₇H₁₇NS, was determined to investigate the relationship between the photoreactivity in solid state and the structure. The geometry was confirmed to be the Z isomer.     

A Pyrene-Modified Serinol Nucleic Acid Nanostructure Converts the Chirality of Threoninol Nucleic Acids into Circularly Polarized Luminescence Signals

Herein is reported a circularly polarized luminescent (CPL) probe that can respond to the chirality of nucleic acids. An achiral nanostructure was prepared by the hybridization of symmetric serinol nucleic acid (SNA) containing pyrene-modified residues. When chiral oligomers that were complementary to the SNA were added, they induced helicity into the SNA nanowire. Efficient circular dichroism (CD) signal amplification was observed when pyrene was attached to uracil bases through a rigid alkynyl linker. Both CPL and CD signals were observed; they depended on the chirality of the added acyclic threoninol nucleic acid (aTNA) oligomer. This system can be used to convert the chirality of chiral biomolecules into chiroptical signals.     

Influence of annealing temperature and Au concentration on the electrical properties of multilayered a-Ge/Au films

Multilayered a-Ge/Au was investigated to realize low-temperature formation of poly-Ge films on insulator. Increasing Au layer thicknesses, peak intensity of crystalline Ge–Ge TO mode increased and amorphous Ge–Ge TO mode decreased. When Au composition ratio is high, the samples are crystallized under eutectic temperature. Annealing temperature at 673 K, all samples with Au layer are crystallized. Crystalline Ge has no strain evaluated by X-ray diffraction and Raman scattering spectroscopy. However, the Au is compressed or expanded in the films with various annealing temperature. It is thought that this phenomenon changes depending on the size of the space in the film. The behavior of electrical resistivity is changed at eutectic temperature.