In dentistry, mechanical analysis applied to dentition is an important issue regardless of whether the evaluation concerns a natural or artificial tooth. This paper describes the mechanobiology of periodontal tissues that receive and respond to occlusal forces and orthodontic treatment forces to maintain a healthy homeostasis. This paper also discusses the effects of accelerating orthodontic teeth movement by the resonance vibration stimulation.
The specific biological response to a mechanical stress is determined by both the properties and magnitude of the applied mechanical stress, in addition to the duration and interval of application to the target cells at the targeted site. Therefore, it is essential to elucidate cell-specific and stimulus-specific biomechanics at the cellular and molecular levels.
This work adds to an emerging field termed mechanobiology that focuses upon understanding mechanosensor /mechanoreceptor molecules that receive signals from mechanical stress, and the mechanism－known as mechanotransduction－by which mechanical stress signals are transmitted into cells. Research outcomes from this field are expected to yield critical information for keeping teeth, bones, and muscles healthy, and increasing the quality of life.
Blood flow is important biological information, and noninvasive and highly accurate blood flow measurement has been required. The blood flow measurement method using near infrared light and visible light has little influence on the human body, so it can be expected to be applied to daily health management. Speckle is one of the measurement methods using light, there are studies on the measurement of the flow velocity and estimation of the static layer thickness corresponding to the blood vessel depth using laser speckle. If it is possible to estimate the fluid layer thickness corresponding to the blood vessel thickness, important biological information such as occlusion of the blood vessel can be obtained. Therefore, in this research, a method to estimate fluid layer thickness and flow velocity simultaneously by laser speckle was proposed. In this paper, as a basic study, we measured the speckle pattern generated in the specimen simulating skin and blood vessel, and investigated the possibility of simultaneous estimation of fluid layer thickness and flow velocity by laser speckle.
By efficiently inducing mesenchymal stem cells into tendon cells, we aimed to construct a simple culture device for regenerating tendon tissue. In this study, we designed a culture substrate that forcibly controls the direction of cultured cells, investigated the gene expression level of stem cells after 2-dimensional free-swelling culture, and clarified the effect of inducing differentiation into tendon cells. We have developed a cell culture membrane with a unidirectional groove on a silicone rubber film. When the stem cells were seeded on the cell culture film, it could be confirmed by fluorescence observation that the cells were strongly oriented in one direction when the groove width was 10 μm. When the groove width was over 10 μm, the cell orientation tended to be weak. On the other hand, according to the analysis result of the gene expression level, when the groove width was narrow, the expression levels of both of type I collagen and tenascin C which specifically expressed in tendon cells increased. As a result, it became possible to easily induce differentiation into tendon cells by narrowing the groove structure.
In this study, in order to clarify the possibility of internal damage in concrete structures, shear tests and ultrasonic testing technique were conducted on normally concrete materials and PIC construction concrete. In addition, the correlation between the internal damage condition of the concrete and the ultrasonic signal was investigated. As a result, a correlation was obtained between the damage state inside the concrete and the sound pressure and sound velocity of ultrasonic waves. It was clarified that the damage condition inside concrete can be estimated by evaluating sound pressure and sound velocity. Furthermore, it is suggested that the ultrasonic testing technique could be used to detect the damage of the concrete before it appears on the material surface.
The Strain Visualization Device developed for structural health monitoring in the Operation and Maintenance of infrastructures can check the amount of strain with the naked eye. In addition, the amount of strain can be calculated with an accuracy of 10 με ± 10 με (2σ) by taking an image with a digital camera and analyzing the image. In applying the Strain Visualization Device to an actual structure, the effect of the shooting angle on the strain calculation accuracy was verified based on the shooting conditions in the field, and the shooting angle that secured the measurement accuracy was clarified. When applied to the strain measurement of a concrete bridge and photographed while paying attention to the shooting angle, the strain can be accurately measured, and the applicability of the strain visualization device to the strain measurement of the actual structure was verified.
Image measurement with high spatial and high temporal resolution is applied on the crack bifurcation. Images of in-plane behavior of bifurcation of the running crack in transparent specimen are captured with the frame rate of 0.2 micro second per frame and the spatial resolution of 0.017mm per pixel. As a result, it is revealed that the crack bifurcated into two or three parallel cracks and they propagate with tiny separation before, so called, bifurcation point. Images of 3 dimensional behavior of bifurcation of the running crack are captured by the ultra high speed camera, which is set inclined to the horizontal plane. The frame rate of the image capturing is 0.2 micro second per frame, and the spatial resolution is 0.058 mm per pixel. As a result, it is observed that the initiation of the crack bifurcation is not the through crack but the partial cracks and bifurcated partial cracks grow up into through cracks after bifurcation.