Boron‐Based Drug Design

The use of the element boron, which is not generally observed in a living body, possesses a high potential for the discovery of new biological activity in pharmaceutical drug design. In this account, we describe our recent developments in boron‐based drug design, including boronic acid containing protein tyrosine kinase inhibitors, proteasome inhibitors, and tubulin polymerization inhibitors, and ortho‐carborane‐containing proteasome activators, hypoxia‐inducible factor 1 inhibitors, and topoisomerase inhibitors. Furthermore, we applied a closo‐dodecaborate as a water‐soluble moiety as well as a boron‐10 source for the design of boron carriers in boron neutron capture therapy, such as boronated porphyrins and boron lipids for a liposomal boron delivery system.     

Laryngeal Gestures During Stop Production Using High-Speed Digital Images

On acoustic and fiberscopic studies of stop consonants, voice onset time and glottal width have been shown to be greatest in heavily aspirated stops, next greater for slightly aspirated stops, and least for unaspirated stops. Integrated activity of the thyroarytenoid and posterior cricoarytenoid muscles has been reported to be involved in differentiating aspirate characteristics of the stops. However, the fine movement of mucosal edges of vocal folds during the production of stops has not been well documented. In recent years, a new method for high-speed digital recording of laryngeal dynamics has made this possible. In the current study, the movements of vocal fold edges were documented during the period of stop production using a fiberscopic system of high-speed digital images. By observing the glottal width and the visual vibratory movements of vocal folds before voice onset, the heavily aspirated stop was characterized as being more prominent and dynamic than the slightly aspirated and unaspirated stops.     

Application of a continued-fraction-based theory to magneto-optical intraband transition in GaAs and CdS

The quantum theory of intraband magneto-optical transition in semiconductors introduced previously in terms of continued-fraction-based power-series-expansion technique is reviewed in connection with examination of temperature- and dimensional-dependence of the width in GaAs and CdS in which piezoelectric scattering is dominant. With the same values of the piezoelectric coupling constant K and the expansion parameter the width in two-dimensions increases with temperature as in three-dimensions. Furthermore, the width becomes smaller uniformly as the dimension is reduced in the direction of static magnetic field in the quantum limit, which is physical. Therefore, the continued-fraction-based theory gives quite good interpretation of the acoustic phonon scattering in the quantum limit.     

Characterization of stable hydrophobic carbon coating and its application in removing organic pollutants

Polydimethylsiloxane (PDMS) thin films were deposited on Ni particles with a mean size of ～1 μm using chemical vapor deposition method. The thin films consisting of these PDMS-covered Ni particles showed a water contact angle higher than 160°, corresponding to the superhydrophobicity. These superhydrophobic films were found to be resistant toward acidic and basic media. The PDMS-covered Ni particles showed high affinity toward non-polar organic solvent such as toluene. Together with an external magnetic field, the PDMS-covered Ni can be used for separating water and toluene from a water/toluene heterogeneous mixture.     

Room-temperature ferromagnetism in hydrothermally treated glassy carbon

Extraordinary room-temperature ferromagnetism was observed in our hydrothermally treated glassy carbon systems, taken to comprise nearly graphitized regions. Strong correlation between the ferromagnetic response and the diamagnetic susceptibility, superposed together, suggests the ferromagnetic long-range order in the graphitic phase to be of itinerant nature. Besides, the graphitization process associated with the itinerant spins and the ferromagnetic order revealed a systematic correlation with the average graphitic cluster size.     

Pressure dependence of acoustic behaviors and refractive index of amorphous Kel F-800 copolymer studied by Brillouin spectroscopy

The pressure dependences of the longitudinal sound velocity and the refractive index of amorphous Kel F-800 copolymer were investigated for pressures up to 13 GPa using high-pressure Brillouin spectroscopy combined with a diamond-anvil-cell technique. The sound velocity increased rapidly with increasing pressure at pressures below ～2 GPa, whereas it showed a mild change at higher pressure values. This was attributed to substantial collapse of effective free volume in this amorphous material. The refractive index could be measured by comparing the Brillouin spectra measured from backward and forward, symmetric scattering geometries. The pressure–density relationship could be obtained by using Lorentz–Lorenz equation based on an assumption of constant polarizability, which was consistent with that reported by previous study.     

Synthesis of an NDPK phosphocarrier domain peptide containing a novel triazolylalanine analogue of phosphohistidine using click chemistry

Click phosphorylation of a propargylated unprotected peptide and phosphoryl azide using chaotrope-assisted Cu(I)-catalyzed 1,3-dipolar cycloaddition enabled a high-yielding and rapid synthesis of a nucleoside diphosphate kinase (NDPK) phosphocarrier domain. The synthesis showcases a valuable synthetic platform for the synthesis of biologically relevant phosphopeptide analogues.