Supramolecular Nanostructures of Chiral Perylene Diimides with Amplified Chirality for High‐Performance Chiroptical Sensing

Chiral supramolecular nanostructures with optoelectronic functions are expected to play a central role in many scientific and technological fields but their practical use remains in its infancy. Here, this paper reports photoconductive chiral organic semiconductors (OSCs) based on perylene diimides with the highest electron mobility among the chiral OSCs and investigates the structure and optoelectronic properties of their homochiral and heterochiral supramolecular assemblies from bottom‐up self‐assembly. Owing to the well‐ordered supramolecular packing, the homochiral nanomaterials exhibit superior charge transport with significantly higher photoresponsivity and dissymmetry factor compared with those of their thin film and monomeric equivalents, which enables highly selective detection of circularly polarized light, for the first time, in visible spectral range. Interestingly, the heterochiral nanostructures assembled from co‐self‐assembly of racemic mixtures show extraordinary chiral self‐discrimination phenomenon, where opposite enantiomeric molecules are packed alternately into heterochiral architectures, leading to completely different optoelectrical performances. In addition, the crystal structures of homochiral and heterochiral nanostructures have first been studied by ab initio X‐ray powder diffraction analysis. These findings give insights into the structure–chiroptical property relationships of chiral supramolecular self‐assemblies and demonstrate the feasibility of supramolecular chirality for high‐performance chiroptical sensing.     

Hall Effect in Bulk‐Doped Organic Single Crystals

The standard technique to separately and simultaneously determine the carrier concentration per unit volume (N , cm^?3) and the mobility (μ) of doped inorganic single crystals is to measure the Hall effect. However, this technique has not been reported for bulk‐doped organic single crystals. Here, the Hall effect in bulk‐doped single‐crystal organic semiconductors is measured. A key feature of this work is the ultraslow co‐deposition technique, which reaches as low as 10^?9 nm s^?1 and enables us to dope homoepitaxial organic single crystals with acceptors at extremely low concentrations of 1 ppm. Both the hole concentration per unit volume (N , cm^?3) and the Hall mobility (μ_H) of bulk‐doped rubrene single crystals, which have a band‐like nature, are systematically observed. It is found that these rubrene single crystals have (i) a high ionization rate and (ii) scattering effects because of lattice disturbances, which are peculiar to this organic single crystal.     

Percolative behavior of transient photoconductivity in metal-free phthalocyanine nanocrystals

Transient photoconductivity in metal-free phthalocyanine (H₂Pc) nanocrystals dispersed in a polyester matrix is investigated. The H₂Pc nanocrystals concentration dependence of transient photoconductivity is examined above the percolation threshold at different temperatures. It is found that the disorder parameter is independent of temperature and increases with concentration of H₂Pc nanocrystals. These findings can successfully be explained by percolative behavior of photocarriers on geometric fractals.     

Fatigue life estimation of adhesive bonded shaft joints

Fatigue tests and analytical investigation of adhesive bonded shaft joints were conducted to propose the estimation method of fatigue strength. Two kinds of adhesive bonded joints were studied: one, shaft joints connected with adhesive coupling, the other, adhesive joints of thin wall tubes to obtain standard fatigue strength. Both pulsating tensile and torsional fatigue tests were conducted with each adhesive joint. Furthermore, the stress distributions under tensile and torsional load conditions were analyzed by finite element method. Based on the analytically computed maximum normal shear stress in the adhesive layer, fatigue strength of the shaft joints was tandardized and compared with that of adhesive joints of thin wall tubes. As a result, it is confirmed that the maximum normal and shear stresses are key parameters for estimating fatigue strength under pulsating tensile and forsional load conditions, respectively. Furthermore, this study indicates an improved method of estimating fatigue strength by using tapered coupling order to reduce the stress concentration at the end of the adhesive layer.     

Enhancement of chalcopyrite leaching by ferrous ions in acidic ferric sulfate solutions

The effects of ferrous ions on chalcopyrite oxidation with ferric ions in 0.1 mol dm⁻³ sulfuric acid solutions were investigated by leaching experiments at 303 K in nitrogen. With high cupric ion concentrations, the chalcopyrite oxidation was enhanced by high concentrations of ferrous ions and copper extraction was mainly controlled by the concentration ratio of ferrous to ferric ions or the redox potential of solutions. Ferrous ions, however, suppressed the chalcopyrite oxidation when cupric ion concentrations were low. A reaction model, which involves chalcopyrite reduction to intermediate Cu₂S by ferrous ions and oxidation of the Cu₂S by ferric ions, was proposed to interpret the results.     

YES1 as a Therapeutic Target for HER2-Positive Breast Cancer after Trastuzumab and Trastuzumab-Emtansine (T-DM1) Resistance Development

Trastuzumab-emtansine (T-DM1) is a therapeutic agent molecularly targeting human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC), and it is especially effective for MBC with resistance to trastuzumab. Although several reports have described T-DM1 resistance, few have examined the mechanism underlying T-DM1 resistance after the development of acquired resistance to trastuzumab. We previously reported that YES1, a member of the Src family, plays an important role in acquired resistance to trastuzumab in HER2-amplified breast cancer cells. We newly established a trastuzumab/T-DM1-dual-resistant cell line and analyzed the resistance mechanisms in this cell line. At first, the T-DM1 effectively inhibited the YES1-amplified trastuzumab-resistant cell line, but resistance to T-DM1 gradually developed. YES1 amplification was further enhanced after acquired resistance to T-DM1 became apparent, and the knockdown of the YES1 or the administration of the Src inhibitor dasatinib restored sensitivity to T-DM1. Our results indicate that YES1 is also strongly associated with T-DM1 resistance after the development of acquired resistance to trastuzumab, and the continuous inhibition of YES1 is important for overcoming resistance to T-DM1.     

Quantum fidelity and dynamical scar states on chaotic billiard system

It is found that the decay rate of the quantum fidelity is suppressed, when the periodic orbit scars in the accumulation of the time-evolving wavefunction become obvious in two-dimensional (2D) nanostructure. The fidelity is numerically evaluated by the time-evolution of the wavepacket inside a 2D chaotic nanostructure: the stadium, which is the typical chaotic system. The suppression is apparent in the Lyapunov regime, where the decay rate does not depend on the strength of the perturbation.