Hiroshi Yoshikawa

Thin hydrogel films based on an ABA triblock copolymer gelator [where A is pH-sensitive poly(2-(diisopropylamino)ethyl methacrylate) (PDPA) and B is biocompatible poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC)] were used as a stimulus-responsive substrate that allows fine adjustment of the mechanical environment experienced by mouse myoblast cells. The hydrogel film elasticity could be reversibly modulated by a factor of 40 via careful pH adjustment without adversely affecting cell viab

With the recent development in pulsed lasers with ultrashort pulse widths or wavelengths, spatially precise, low-damage processing by femtosecond or deep-UV laser ablation has shown promise for the production of protein single crystals suitable for X-ray crystallography. Femtosecond laser processing of supersaturated solutions can shorten the protein nucleation period or can induce nucleation at low supersaturation, which improves the crystal quality of various proteins including membrane protei

The crystallization of urea was triggered using an intense 800 nm femtosecond laser that was focused to a supersaturated solution through an objective lens. An explosive crystallization proceeded in the entire sample glass tube for a few seconds at a concentration that no spontaneous nucleation occurred even after a few days. The crystallization was precisely monitored using a high-speed complementary metal oxide semiconductor (CMOS) camera attached to a microscope with a time resolution of 100

Growth of urea crystals in a supersaturated solution of urea was spatially controlled by irradiation with a femtosecond laser pulse. When a needlelike urea crystal was irradiated by a single femtosecond laser pulse with wavelength of 800 or 1470 nm through an objective lens, a new needlelike crystal grew from the laser focal spot (approximately micrometer sized). The number of the laser-induced subsequent crystals increased with laser energy. However, such crystal growth could not be induced by

This paper presents a definition of the long-run equilibrium exchange rate that emphasizes the role of supply factors in addition to the more traditional price differential variables. Using this definition, we estimate the long-run equilibrium yen-dollar rate during the period of 1973-87. This calculation demonstrates that supply factors are in fact very important determinants of the long-run movement of the exchange rate. Despite the central role the exchange rates play in the economy, economis

We have quantitatively determined how the morphology and adhesion strength of myoblast cells can be regulated by photocurable gelatin gels, whose mechanical properties can be fine-tuned by a factor of 10(3) (0.1 kPa ≤ E ≤ 140 kPa). The use of such gels allows for the investigation of mechanosensing of cells not only near the natural mechanical microenvironments (E ~ 10 kPa) but also far below and beyond of the natural condition. Optical microscopy and statistical image analysis revealed that myo

We fabricated a planar aperture-mounted (PAM) slider by use of a focused ion beam to demonstrate fast data acquisition for near-field optical data storage. The aperture (200 nm x 500 nm) was formed upon the Ti-coated air-bearing surface of the slider and was directly illuminated with a laser (lambda = 532 nm) beam spot by use of an objective lens (N.A., 0.55). The light transmitted through the aperture was modulated by a Ti-coated SiO(2) disk with 200- and 400-nm-wide line-and-space (L&S) patter