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Predicting the dynamics of an electrically charged drop impacting a solid surface is of great importance in various industrial applications such as spray coating and painting. An impacting drop decelerates immediately before the touch-down by the lubrication pressure of the intervening air. The pressure build-up forms a dimple resulting in the entrapment of bubbles under the drop. We measured and visualized the dimple and bubble formations using high-speed interferometry and back-light imaging techniques by focusing on the effect of the electrostatic charge on the surface deformation. We clarified that the dimple size decreased, and the kink of the dimple became more flattened with increasing the charge, which resulted in forming a micro-bubble band around a central bubble. By comparing the dimple profile obtained with interferometry and bubble images, we revealed that an air layer, thinner than 266 nm, raptures into small pieces forming a microbubble band while a thicker air layer collapses into a bubble. Replacing a substrate from conductive to dielectric hinders the decrease in dimple volume, confirming Maxwell stress acting between the drop bottom surface and the substrate plays a crucial role in determining the bubble entrapment. [ABSTRACT FROM AUTHOR]

We develop a novel equipment that levitates giant drops, size of which is larger than the capillary length, over a moving wall. Generally, the levitation of giant drops is challenging since a drop larger than capillary length deforms and breaks up easily. We overcome this difficulty by equipping a special-shaped glass hollow cylinder. The novel equipment successfully levitates a drop of 5 ml in volume, which is more than 500 times larger than volumes of levitating drops reported in previous works. Remarkably, the giant drop levitates more than 24 hours for the special-shaped cylinder and a liquid film over the cylinder surface. This containerless manipulation of giant drops may open a new door for new method of material science and high-precision chemical analysis. In addition, we investigate the levitation mechanism of a giant drop over a moving wall. We adopt interferometry to observe the bottom shape of the drop which is complex because of the air flow between the drop and the moving wall. It is found that, when the drop size is large enough, the bottom shape of the drop shows surface waves, which has not been reported by any previous researches. Phase speed and wavelength of the surface wave vary with experimental parameters (i.e. wall velocity and drop diameter). Interestingly, both phase speed and wavelength have a linear relationship to the product of wall velocity and drop diameter. [ABSTRACT FROM AUTHOR]

Optical coherence tomography (OCT) is an observation technique utilizing optical interferometry. Images of the internal structure of opaque materials can be obtained dynamically and three-dimensionally in a few seconds. In this work, the internal structures of ceramic sintered body and slurry was observed by OCT. In the case of Al2O3 ceramics, an artificially induced spherical defect having smaller than 50 μm in diameter which lies 700 μm below the top surface was observed successfully. Furthermore, it was observed that the internal structure of Al2O3 slurry was drastically changed during drying, followed by formation of a crack in the dried green body. [ABSTRACT FROM AUTHOR]

Using canine temporal bone, perforations were surgically prepared at the anterior, inferior and posterior parts of the tympanic membrane, and the influences of these perforations on the tympanic vibration were observed and analyzed by holographic interferometry. Normal canine tympanic membrane had its respective single maximum amplitude points at its anterior and posterior parts at a frequency from the low compass to 2 kHz or so and showed a concentric circular vibration pattern centering mainly there around. At 3 and 4 kHz or so, the posterior and anterior parts began to show their respective sectional vibrations and with an increase in frequency, showed their further complicated multi-sectional vibrations. Resonance frequency was 1 or 2 kHz or so. The tympanic vibration following the preparation of perforations was as follows: 1) For the posterior perforation, the frequency at which the anterior sectional vibration began passed to a higher frequency, while for the other perforations, no change was noted in vibration pattern of the remaining tympanic membrane. 2) Comparative examination of the vibration amplitude at the mallear tip revealed that for a small perforation, no change in resonance frequency was noted regardless of the location of perforation and an increase in vibration amplitude was noted near the resonance frequency. 3) For the anterior perforation, no change in resonance frequency was noted even with an expansion of perforation and an increase in vibration amplitude was noted near the resonance frequency. 4) For the posterior and inferior perforations, the resonance frequency passed to a higher frequency with an expansion of perforation and an increase in vibration amplitude was noted near the resonance frequency.(ABSTRACT TRUNCATED AT 250 WORDS)

Sclerosis of auditory ossicle was experimentally induced by fixation of the stapes, and its effect on the tympanic membrane vibration was examined using fresh 10 canine temporal bones by means of holographic interferometry. By changing the sound pressure (from 90 to 110dB) and the frequency (from 250Hz to 8kHz) in steps, vibration of the membrane was induced in a free field. At each frequency, the vibration of the membrane was photographed by the time averaged method using He-Ne laser. A small hole was created in the tympanic bulla and the stapes was fixed with an adhesive (Alon Alpha), followed by closure of the hole. Before stapes fixation, the posterior part of the membrane showed a simple vibration pattern, forming cocentric interference circles at frequencies from 250Hz to 2kHz. At 3kHz, segmental vibration began to be noted, and complex segmental vibration was seen at frequencies 4.5 and 6kHz. The vibration after stapes fixation became simpler at frequencies over 3kHz, accompanied by decrease in the number of segmental vibrations. Vibration amplitude in the posterior part of the membrane decreased from 250Hz to 3kHz, while it increased at frequencies over 4kHz. In the anterior part of the membrane, the amplitude decreased at frequencies under 2kHz, remained unchanged at 3kHz and increased at frequencies over 4kHz after stapes fixation. In the tip of the manubrium mallei, the amplitude decreased at frequencies under 3kHz and increased at frequencies over 4kHz. Thus, a shift of peak vibration to high sound region was observed after stapes fixation at every part of tympanic membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of middle ear liquid on the tympanic membrane (TM) vibration was studied using the holographic interferometry. The physiological saline solution was injected into the middle ear cavity of the canine temporal bone. The liquid volume in the middle ear cavity was changed into 3 grades in order to observe the difference of the vibration pattern between them. The vibratory patterns of a normal canine TM remained unchanged in their first mode up to a frequency of approximately 2 kHz. In this mode, there were peak displacement regions in the posterior and anterior quadrants. The TM vibrations showed sectional patterns, above 3 kHz in the posterior and above 4 kHz in the anterior. After liquid retention, the following were observed. 1. The frequency at which sectional patterns occurred shifted to a lower frequency in the immerged portion, but showed no definite tendency in the unimmerged portion. 2. Maximum amplitudes of the anterior and posterior quadrants of the TM and the mallar tip shifted to somewhat higher frequencies for the liquid volume below the level of the tip portion, but contrary, shifted to lower frequencies for the liquid volume there above. 3. The ossicular chain tended not to make normal function for the TM vibration with an increase of liquid volume.

The effects of positive and negative pressure in the middle ear on tympanic membrane (TM) vibrations were studied in twenty canine temporal bones by holographic interferometry. The displacement of the TM was measured by moiré topography. 1) When pressure was applied to the tympanic cavity, the curvature of the TM became small under negative pressure and large under positive pressure, with the displacement being greater under positive pressure. 2) Without pressure load, the vibration pattern below 2 kHz was simple and there were peak displacement regions in the posterior and anterior parts of the membrane and the peaks occurred approximately halfway along the manubrium. The TM vibrations showed sectional patterns, above 3 kHz in the posterior and above 4 kHz in the anterior. The amplitude of the anterior peak was larger than that of the mallear tip, but smaller than that of the posterior. 3) At frequencies below 2 kHz, the vibration pattern was not affected by negative pressure load. At frequencies of 3 kHz or higher, the sectional patterns changed into the simpler patterns and the sectional vibrations diminished as the pressure increased. 4) Below 2 kHz, the TM amplitude decreased with increasing negative pressure. Above 3 kH, the amplitude showed an initial increase but decreased at higher negative pressure loading. With the amplitude of the mallear tip, the same tendency was observed. The resonance frequency shifted to a higher frequency range with pressure loading. 5) Under positive pressure, the vibration pattern remained unchanged below 2 kHz, and above 3 kH, sectional vibrations changed to the simple vibrations.(ABSTRACT TRUNCATED AT 250 WORDS)

The Moiré method has been widely used in mass school screening for early detection of scoliosis. A new type of automatic analyser for scoliosis, which is the conceptual heir of the Moiré method, was developed. This new apparatus consists of a slide projector, video camera and microcomputer system using the principle of three-dimensional robot vision technology. Using this new method, the measurement for one patient is done automatically in less than a half minute. A good correlation is noted between the degrees measured by the new method and Cobb angles on X-ray film. Results suggest the usefulness of this system for the mass screening of scoliosis and to judge the effects of treatment.

Dynamic posture of 127 normal males, 144 normal females and 68 scoliotic patients was studied by a system utilizing Moiré topography, a video recorder and Apple II microcomputer system. The normal group was divided into five subgroups by age and the scoliotic group into three subgroups according to the Cobb angle. The following results were obtained: The clockwise rotation during on-the-spot marching was larger in early juvenile females. The rotation movement during on-the-spot marching was almost symmetrical in normal individuals older than seven years of age. In scoliotic patients, the trunk movement during on-the-spot marching was asymmetric. The angle of rotation during on-the-spot marching was significantly larger in scoliotic patients than in normal adolescent females. A propensity was found that the greater the scoliosis curve was the less was the rotation angle of the trunk during on-the-spot marching.

Since 1978 school screening of scoliosis has been performed every year by the system established by the author consisting of 4 step examinations in Niigata City. The initial examination is carried out with forward bending test associated with swing maneuver by school nurses or school doctors in all school boys and girls from the 4th grade of elementary school to the 3rd grade of junior-high school. The incidence of scoliosis with deformity of more than 20 degrees has been nearly constant ranging from 0.06% to 0.09% in elementary school, and 0.35% to 0.40% in junior-high school. The author compared the number and treatment of the patients of Niigata City seen in our scoliosis clinic in the period of 7 years before and after starting this program. After this program started, the number of the patients with scoliosis of more than 20 degrees has increased by 4 times. The number of surgery in adolescent idiopathic scoliosis, on the contrary, has markedly decreased.