Showing papers by "Hiroshi Yokoyama published in 1995"

Myxobolus cultus n. sp. (Myxosporea: Myxobolidae) in the goldfish Carassius auratus transformed from the actinosporean stage in the oligochaete Branchiura sowerbyi.

Abstract: A new myxosporean Myxobolus cultus n. sp. was found in experimentally infected goldfish Carassius auratus exposed to actinosporean spores from the oligochaete Branchiura sowerbyi (Tubificidae). At 2-4 mo following initial exposure, spores of M. cultus were observed in the cartilage of goldfish. A lymphocytic infiltrate surrounded the pseudocysts. Some pseudocysts were destroyed and spores had been engulfed by phagocytes. Phagocytized spores were also found in the epidermis of skin and within melanomacrophage centers in the kidney.

Two-Dimensional Dynamic Patterns in Illuminated Langmuir Monolayers

Abstract: Purely light-driven spatiotemporal pattern formation has been found to take place in a liquid-crystalline Langmuir monolayer consisting of an amphiphilic azobenzene derivative, undergoing the trans ↔ cis photoisomerizations. The Langmuir monolayer is in a smectic-C-like liquid crystal phase, whose two-dimensional orientation is easily perturbed by slight conformation changes in the constituent molecules. On illumination with a linearly polarized light, a collective and global in-plane reorientation of the azobenzene chromophores is induced over an existing static stripe texture, which finally yields polarization-dependent steady state orientational patterns. Prolonged photoexcitation generates sustained traveling and solitary waves, associated with variations in molecular tilt directions. The liquid crystallinity of the monolayer allows these orientational responses to occur even at an extremely weak light power at least 2 orders of magnitude smaller than that known in previous photoreorientation studies of azobenzene chromophores.

Effects of Rubbing and Temperature Dependence of Polar Anchoring Strength of Homogeneously Aligned Nematic Liquid Crystal on Polyimide Langmuir-Blodgett Orientation Films.

Abstract: The effect of rubbing on the polyimide (PI) Langmuir-Blodgett (LB) surface-alignment films has been successfully evaluated by observing the temperature dependence of the polar anchoring strength of nematic liquid crystal 4-cyano-4'-n-pentylbiphenyl (5CB). Upon rubbing, the PI-LB films showed a significant increase in the anchoring strength. The anchoring strength showed a nearly divergent decrease toward the clearing temperature, which is a manifestation of the diminished surface ordering, as previously pointed out for obliquely evaporated SiO films. Based on the van der Waals theory developed by Yokoyama et al. [J. Appl. Phys. 61 (1987) 4501], the intrinsic parts of the anchoring energy have been obtained as a function of temperature and found to undergo nearly one order of magnitude increase on rubbing. The polar anchoring energies for 5CB were strongly related to the surface order parameter on PI-LB films.

Fresnel Formula for Optically Anisotropic Langmuir Monolayers: An Application to Brewster Angle Microscopy

Abstract: An approximate yet highly accurate Fresnel formula, describing the reflection from optically anisotropic Langmuir monolayers, is derived in a simple closed form The utility of the Fresnel formula is demonstrated by an application to Brewster angle microscopy

Enhanced Photocurrent in Organic Photoelectric Cells Based on Surface Plasmon Excitations

Abstract: Surface plasmons (SP) were excited on both of the electrodes of organic photoelectric cells of Al/copper phthalocyanine/Ag structure using the attenuated total reflection method to examine the influence of excitation of SP on photoelectric effects. A marked increase in the photocurrent was caused by the excitation of SP. Origin of the enhancement of photocurrent due to excitation of SP is discussed based on the experimental results and the calculations of the electric field inside the cell showing that the enhancement cannot be explained only by the intensity of electric field.

Nanoscale evaluation of structure and surface potential of gated field emitters by scanning Maxwell-stress microscope

Abstract: Both the structural and surface potential images of gated field emitters (GFEs) were measured using a scanning Maxwell-stress microscope (SMM) in air. Si cone-shaped and Mo disk-edge GFEs were measured. The experimental results clearly revealed differences in the surface potential for various materials and irregularities in the GFE structures which were too small to be found by conventional scanning electron microscope observations. It was also found that the surface potential of Si was rather flat even in the emitter tip apex.

Imaging Local Electric Forces in Organic Thin Films by Scanning Maxwell Stress Microscopy

Abstract: By use of the heterodyne force-detected scanning Maxwell stress microscope (HFD-SMM), simultaneous imaging of topography, surface potential, and high-frequency dielectric dispersion has been performed for a phase-separated phospholipid monolayer and a vacuum deposited phthalocyanine thin film. With the use of an in-house fabricated highly sharp Si-tip, higher resolution images have been obtained.